1. A load balancing method for a wireless local area network (LAN) having a plurality of access points, each of the access points has a plurality of queues, and the load balancing method comprises: assigning each of the queues to a plurality of corresponding classes of service; mapping each of the corresponding classes of service to a plurality of virtual local area networks (VLANs); mapping each of a plurality of identifiers to a VLAN tag corresponding to one of the VLANs; making a load balancing decision by a load balancing module according to the traffic conditions and bandwidth availability of each of a plurality of traffic priority classes based on a corresponding class of service, and taking the VLANs on a per VLAN tag into consideration when making the load balancing decision by the load balancing module; and performing load balancing by the load balancing module according to the corresponding traffic priority class within the same VLAN.