diff --git a/app.py b/app.py
index 834b1f1..06c9cab 100644
--- a/app.py
+++ b/app.py
@@ -365,9 +365,11 @@ def create_ca(ca_name, common_name, organization, organizational_unit, country,
 
 def create_certificate(ca_id, common_name, san_dns, san_ip, organization, organizational_unit,
                        country, state, locality, key_size, days_valid, created_by):
+    """创建证书并返回证书ID"""
     # 获取CA信息
     ca = get_ca_by_id(ca_id)
     if not ca:
+        print(f"CA ID {ca_id} 不存在")
         return None
 
     # 创建证书目录
@@ -378,132 +380,146 @@ def create_certificate(ca_id, common_name, san_dns, san_ip, organization, organi
     csr_path = os.path.join(cert_dir, f"{common_name}.csr")
     cert_path = os.path.join(cert_dir, f"{common_name}.crt")
 
-    # 生成私钥
-    subprocess.run([
-        'openssl', 'genrsa', '-out', key_path, str(key_size)
-    ], check=True)
+    # 1. 生成私钥
+    try:
+        subprocess.run([
+            'openssl', 'genrsa', '-out', key_path, str(key_size)
+        ], check=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
+    except subprocess.CalledProcessError as e:
+        print(f"生成私钥失败: {e.stderr.decode()}")
+        return None
 
-    # 创建CSR配置文件
-    csr_config = f"""[req]
-    default_bits = {key_size}
-    prompt = no
-    default_md = sha256
-    distinguished_name = dn
-    """
-
-    # 只有在有SAN时才添加扩展部分
+    # 2. 创建CSR配置文件
     has_san = bool(san_dns or san_ip)
+    dns_entries = [dns.strip() for dns in san_dns.split(',') if dns.strip()] if san_dns else []
+    ip_entries = [ip.strip() for ip in san_ip.split(',') if ip.strip()] if san_ip else []
+
+    # 构建CSR配置
+    csr_config = f"""[req]
+default_bits = {key_size}
+prompt = no
+default_md = sha256
+distinguished_name = dn
+"""
+
     if has_san:
         csr_config += "req_extensions = req_ext\n"
 
     csr_config += f"""
-    [dn]
-    CN = {common_name}
-    O = {organization}
-    OU = {organizational_unit}
-    C = {country}
-    ST = {state}
-    L = {locality}
-    """
+[dn]
+CN = {common_name}
+O = {organization}
+OU = {organizational_unit}
+C = {country}
+ST = {state}
+L = {locality}
+"""
 
     if has_san:
         csr_config += """
-    [req_ext]
-    basicConstraints = CA:FALSE
-    keyUsage = digitalSignature, keyEncipherment
-    subjectAltName = @alt_names
-    extendedKeyUsage = serverAuth, clientAuth
+[req_ext]
+basicConstraints = CA:FALSE
+keyUsage = digitalSignature, keyEncipherment
+subjectAltName = @alt_names
+extendedKeyUsage = serverAuth, clientAuth
 
-    [alt_names]"""
+[alt_names]"""
 
         # 添加DNS SAN条目
-        if san_dns:
-            dns_entries = [dns.strip() for dns in san_dns.split(',') if dns.strip()]
-            for i, dns in enumerate(dns_entries, 1):
-                csr_config += f"\nDNS.{i} = {dns}"
+        for i, dns in enumerate(dns_entries, 1):
+            csr_config += f"\nDNS.{i} = {dns}"
 
         # 添加IP SAN条目
-        if san_ip:
-            ip_entries = [ip.strip() for ip in san_ip.split(',') if ip.strip()]
-            for i, ip in enumerate(ip_entries, 1):
-                csr_config += f"\nIP.{i} = {ip}"
+        for i, ip in enumerate(ip_entries, 1):
+            csr_config += f"\nIP.{i} = {ip}"
 
-    # 确保配置文件不以空行结尾
-    csr_config = csr_config.strip()
+    # 写入CSR配置文件
+    csr_config_path = os.path.join(cert_dir, 'csr_config.cnf')
+    with open(csr_config_path, 'w') as f:
+        f.write(csr_config.strip())  # 确保没有多余空行
 
-    config_path = os.path.join(cert_dir, 'csr_config.cnf')
-    with open(config_path, 'w') as f:
-        f.write(csr_config)
-
-    # 生成CSR
+    # 3. 生成CSR
     try:
         subprocess.run([
-            'openssl', 'req', '-new', '-key', key_path, '-out', csr_path,
-            '-config', config_path
-        ], check=True)
+            'openssl', 'req', '-new', '-key', key_path,
+            '-out', csr_path, '-config', csr_config_path
+        ], check=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
     except subprocess.CalledProcessError as e:
-        print(f"OpenSSL错误: {e}")
+        print(f"生成CSR失败: {e.stderr.decode()}")
         print("CSR配置文件内容:")
         print(csr_config)
         return None
 
-    # 使用CA签名证书（添加-extfile参数）
+    # 4. 创建证书扩展配置文件
+    ext_config = """authorityKeyIdentifier=keyid,issuer
+basicConstraints=CA:FALSE
+keyUsage=digitalSignature, keyEncipherment
+extendedKeyUsage=serverAuth, clientAuth
+"""
+
+    if has_san:
+        ext_config += "subjectAltName=@alt_names\n\n[alt_names]\n"
+
+        # 添加DNS SAN条目
+        for i, dns in enumerate(dns_entries, 1):
+            ext_config += f"DNS.{i} = {dns}\n"
+
+        # 添加IP SAN条目
+        for i, ip in enumerate(ip_entries, 1):
+            ext_config += f"IP.{i} = {ip}\n"
+
+    ext_config_path = os.path.join(cert_dir, 'ext.cnf')
+    with open(ext_config_path, 'w') as f:
+        f.write(ext_config.strip())
+
+    # 5. 使用CA签名证书
     try:
-        # 创建扩展配置文件
-        ext_config = f"""
-        authorityKeyIdentifier=keyid,issuer
-        basicConstraints=CA:FALSE
-        keyUsage=digitalSignature, keyEncipherment
-        extendedKeyUsage=serverAuth, clientAuth
-        subjectAltName=@alt_names
+        cmd = [
+            'openssl', 'x509', '-req', '-in', csr_path,
+            '-CA', ca['cert_path'], '-CAkey', ca['key_path'],
+            '-CAcreateserial', '-out', cert_path,
+            '-days', str(days_valid), '-sha256'
+        ]
 
-        [alt_names]"""
+        # 只有有扩展内容时才添加-extfile参数
+        if os.path.getsize(ext_config_path) > 0:
+            cmd.extend(['-extfile', ext_config_path])
 
-        if san_dns:
-            for i, dns in enumerate(dns_entries, 1):
-                ext_config += f"\nDNS.{i} = {dns}"
-
-        if san_ip:
-            for i, ip in enumerate(ip_entries, 1):
-                ext_config += f"\nIP.{i} = {ip}"
-
-        ext_path = os.path.join(cert_dir, 'ext.cnf')
-        with open(ext_path, 'w') as f:
-            f.write(ext_config.strip())
-
-        subprocess.run([
-            'openssl', 'x509', '-req', '-in', csr_path, '-CA', ca['cert_path'],
-            '-CAkey', ca['key_path'], '-CAcreateserial', '-out', cert_path,
-            '-days', str(days_valid), '-sha256', '-extfile', ext_path
-        ], check=True)
+        subprocess.run(cmd, check=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
     except subprocess.CalledProcessError as e:
-        print(f"签名证书错误: {e}")
+        print(f"证书签名失败: {e.stderr.decode()}")
+        print("扩展配置文件内容:")
+        print(ext_config)
         return None
 
-    # 计算过期时间
+    # 6. 保存到数据库
     expires_at = datetime.now() + timedelta(days=days_valid)
-
-    # 保存到数据库
     conn = get_db_connection()
     if conn:
         try:
             cursor = conn.cursor()
             cursor.execute("""
                 INSERT INTO certificates 
-                (common_name, san_dns, san_ip, organization, organizational_unit, country, state, locality,
-                 key_size, days_valid, cert_path, key_path, csr_path, ca_id, created_by, expires_at)
+                (common_name, san_dns, san_ip, organization, organizational_unit, 
+                 country, state, locality, key_size, days_valid, cert_path, 
+                 key_path, csr_path, ca_id, created_by, expires_at)
                 VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
-            """, (common_name, san_dns, san_ip, organization, organizational_unit, country, state, locality,
-                  key_size, days_valid, cert_path, key_path, csr_path, ca_id, created_by, expires_at))
+            """, (
+                common_name, san_dns, san_ip, organization, organizational_unit,
+                country, state, locality, key_size, days_valid, cert_path,
+                key_path, csr_path, ca_id, created_by, expires_at
+            ))
             conn.commit()
             return cursor.lastrowid
         except Error as e:
-            print(f"Database error: {e}")
+            print(f"数据库错误: {e}")
+            conn.rollback()
             return None
         finally:
             if conn.is_connected():
                 cursor.close()
                 conn.close()
+
     return None