The invention discloses a seamless switching method in a 802.11 wireless local area network, which is applied to business office environment and other scenes where wireless APs are densely deployed and a client often needs to be moved. An SDN concept-based network framework is adopted, a virtual access point (VAP) is constructed for connection between an abstract AP and the Client. The VAP contains all information needed when the Client and the AP build connection, generation and removal of the VAP on the AP are controlled by a controller so as to enable the Client and the AP to build connection or cut off connection. When the Client is moved in the WLAN, the application program in the controller senses the strength of signals sent by the Client and received by the AP in the network through an issue/subscription mechanism to judge the AP nearest to the Client and connection is thus built. Control of the controller on the VAP and Client movement are almost synchronous, and seamless switching is thus realized.