An analysis of WLAN security mechanisms of wired equivalent privacy (WEP) and Wi-Fi protected access (WPA) discovers that the current literature is not totally creditable in its judgment on the security value of WEP and WPA.Based on the respective performances of WEP and WPA under certain typical attacks,this paper substantiates the judgment that WEP has quite a few vulnerabilities concerning confidentiality and integrity,but at the same time challenges the judgment on WPA with that WPA is robust enough to confront potential typical attacks and is not so unreliable as the current literature believes,although it has some vulnerabilities in its message integrity code (MIC).