A WAPI unicast secret key negotiation method includes the following steps: 1 a authenticator entity adds a message integrity code onto a unicast secret key negotiation request packet, and transmits it to a authentication supplicant entity; 2 after the authentication supplicant entity receives the unicast secret key negotiation request packet, it performs validation, and it discards the packet directly if it is not correct; the authentication supplicant entity performs other validation if it is correct; when the validation is successful, it responds a unicast secret key negotiation response packet to the authenticator entity; 3 after the authenticator entity receives the unicast secret key negotiation response packet, it performs validation, if the validation is successful, it responds the unicast secret key negotiation acknowledge packet to the authentication supplicant entity; 4 after the authentication supplicant entity receives the unicast secret key negotiation acknowledge packet, it performs validation, if the validation is successful it negotiates and obtains a consistent unicast session secret key. The present invention resolves the DoS attacking problem which exists in the unicast secret key management protocol in the present WAPI security mechanism.