The present invention relates to a method for the secure access of mobile terminal to the Wireless Local Area Network (WLAN) and for secure data communication via wireless link, which, combining the common key encryption technology and the symmetry encryption technology, has resolved the failure in WLAN to provide effective control on secure MT access, and overcome the limitation on the confidentiality of the data communication via wireless link. When MT logs on AP, both parts must perform the certificate authentication through AS. Only the MT holding the legitimate certificate can access to AP holing the legitimate certificate; MT and AP perform the negotiation of common key for conversation, complete the dynamic revision of the secret key in each authentication, each secret key and in the process of conversation to achieve confidential data communication. Anyway, the method has not only achieved control on the access of MT, but also ensured the security of MT access and high confidentiality of communication.