A method for implementing network security access control, comprising: receiving, by a server; terminal identity information that is encrypted in a bi-directional encryption mode and forwarded by a switch, wherein the bi-directional encryption comprises Data Encryption Standard, DES, 3DES or Advanced Encryption Standard, AES; decrypting, by the server, the terminal identity information encrypted in the bidirectional encryption mode, and authenticating the decrypted terminal identity information; returning, by the server, an authentication result to the switch, so that the switch controls access of a terminal to a network according to the authentication result, wherein the returning the authentication result to the switch comprises: returning the authentication result indicating that the terminal has a network, access right to the switch so that the switch opens a port by using which the terminal accesses the network; or, returning the authentication result indicating that the terminal does not have a network access right to the switch so that the switched closes a port by using which the terminal accesses the network; encrypting, by the server, the decrypted terminal identity information in a solo-directional encryption mode, wherein the solo-directional encryption comprises Message-Digest Algorithm 5, MD5, or Secure Hash Algorithm, SHA1; authenticating, by the server, the terminal identity information encrypted in the solo-directional encryption mode; returning, by the server, an authentication result to a security access control gateway, so that the security access control gateway controls access of the terminal to network resources according to the authentication result, wherein the authentication result returned to the security access control gateway comprises a level of a network access right of the terminal so that the security access control gateway opens network resources of an specified IP address segment; and delivering, by the server, a security policy to a security control module on the terminal, so that the security control module monitors the terminal according to the security policy. receiving, by a server; terminal identity information that is encrypted in a bi-directional encryption mode and forwarded by a switch, wherein the bi-directional encryption comprises Data Encryption Standard, DES, 3DES or Advanced Encryption Standard, AES; decrypting, by the server, the terminal identity information encrypted in the bidirectional encryption mode, and authenticating the decrypted terminal identity information; returning, by the server, an authentication result to the switch, so that the switch controls access of a terminal to a network according to the authentication result, wherein the returning the authentication result to the switch comprises: returning the authentication result indicating that the terminal has a network, access right to the switch so that the switch opens a port by using which the terminal accesses the network; or, returning the authentication result indicating that the terminal does not have a network access right to the switch so that the switched closes a port by using which the terminal accesses the network; encrypting, by the server, the decrypted terminal identity information in a solo-directional encryption mode, wherein the solo-directional encryption comprises Message-Digest Algorithm 5, MD5, or Secure Hash Algorithm, SHA1; authenticating, by the server, the terminal identity information encrypted in the solo-directional encryption mode; returning, by the server, an authentication result to a security access control gateway, so that the security access control gateway controls access of the terminal to network resources according to the authentication result, wherein the authentication result returned to the security access control gateway comprises a level of a network access right of the terminal so that the security access control gateway opens network resources of an specified IP address segment; and delivering, by the server, a security policy to a security control module on the terminal, so that the security control module monitors the terminal according to the security policy.