The invention provides a channel load balancing system and method for a multi-channel wireless local area network. The system includes a controller connected to the wireless local area network and a plurality of access points arranged in N channels that are not in mutual interference. The access points are used for generating detection frame messages and uploading the messages to the controller when receiving detection frames sent by a terminal, wherein the detection frame messages include wireless signal header information and terminal MAC addresses. The access points are also used for sending responses of the detection frame to the terminal when receiving responding messages delivered by the controller and thereby establishing connection with the terminal. The controller is used for selecting the channels and the access points for access of the wireless local network of the terminal sending the original detection frame according to the detection frame messages uploaded by the access points. The invention also provides the corresponding channel load balancing method. According to the invention, WLAN channel load balance can be realized at a low cost. Besides, the system and method provided by the invention are accessible to terminals, so that promotion is facilitated.