A method for pre-authenticating a wireless local area network terminal and a wireless local area network system. The pre-authentication method includes after a current access point (AP) which has set up security association with a station (STA) receiving a pre-authentication start packet sent by the STA, the current AP interacting with a destination AP to verify certificates of the current AP and the destination AP for each other. If a certificate of the destination AP is verified to be valid, the current AP sending key information of the security association set up with the STA by the current AP to the destination AP, and the destination AP saving the key information, the key information including a basic key generated by negotiation between the STA and the current AP.