Abstract: As a security technology，WLAN intrusion detection technology plays an important role in the security of the WLAN network and system. Some intrusion ways are analyzed， and the intrusion detection techniques are discussed. Architecture of the WLAN intrusiondetection system (WIDS) is designed. The logic structures are given, functions in the WIDS and implementation technique are expatiated detailed finally, and the realization of the WIDS is researched and discussed.

Key words: wireless local area network, intrusion, detection, network security, rule base