diff --git a/app.py b/app.py
index 7b57660..834b1f1 100644
--- a/app.py
+++ b/app.py
@@ -385,38 +385,48 @@ def create_certificate(ca_id, common_name, san_dns, san_ip, organization, organi
 
     # 创建CSR配置文件
     csr_config = f"""[req]
-default_bits = {key_size}
-prompt = no
-default_md = sha256
-distinguished_name = dn
-req_extensions = req_ext
+    default_bits = {key_size}
+    prompt = no
+    default_md = sha256
+    distinguished_name = dn
+    """
 
-[dn]
-CN = {common_name}
-O = {organization}
-OU = {organizational_unit}
-C = {country}
-ST = {state}
-L = {locality}
+    # 只有在有SAN时才添加扩展部分
+    has_san = bool(san_dns or san_ip)
+    if has_san:
+        csr_config += "req_extensions = req_ext\n"
 
-[req_ext]
-basicConstraints = CA:FALSE
-keyUsage = digitalSignature, keyEncipherment
-subjectAltName = @alt_names
-extendedKeyUsage = serverAuth, clientAuth
+    csr_config += f"""
+    [dn]
+    CN = {common_name}
+    O = {organization}
+    OU = {organizational_unit}
+    C = {country}
+    ST = {state}
+    L = {locality}
+    """
 
-[alt_names]"""
+    if has_san:
+        csr_config += """
+    [req_ext]
+    basicConstraints = CA:FALSE
+    keyUsage = digitalSignature, keyEncipherment
+    subjectAltName = @alt_names
+    extendedKeyUsage = serverAuth, clientAuth
 
-    # 添加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}"
+    [alt_names]"""
 
-    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}"
+        # 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}"
+
+        # 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}"
 
     # 确保配置文件不以空行结尾
     csr_config = csr_config.strip()