This text first gives an introduction of WLAN 802.11a standards work principle, structure and key technique. The most important part in this text is WLAN wireless channel s big-scale fading and small-scale fading and their modeling and simulating methods. The models of big-scale fading and small-scale fading are selected and the wireless channel is build for 802.11a’s link level simulation. At last the simulation result is analyzed, and the result indicates that the wireless channel is right.-This text first gives an introduction of WLAN 802.11a standards　work principle, structure and key technique. The most important part in this text is WLAN wireless channel s big-scale fading and small-scale fading and their modeling and simulating methods. The models of big-scale fading and small-scale fading are selected and the wireless channel is build for 802.11a’s link level simulation. At last the simulation result is analyzed, and the result indicates that the wireless channel is right.