A cellular-network-assisted wireless local area network, WLAN, channel switch announcement method, comprising the following steps: before a WLAN access point, AP, performs channel switching, the WLAN AP delivering channel switch announcement signaling to associated user equipments in a broadcast manner, and sending channel switch announcement request signaling to a cellular network base station that serves the associated user equipments, the characterized in that channel switch announcement request signaling comprises: a user equipment ID for the user equipment that cannot receive the channel switch announcement signaling as predicted by the WLAN AP, an ID of the WLAN AP, a channel switch mode of the WLAN AP, a channel before switching, a channel after switching, and a time for channel switching; the cellular network base station, after receiving the channel switch announcement request signaling, sending the channel switch announcement request signaling, by using radio resource control, RRC, control signaling, to a user equipment in an idle mode via a cellular link air interface, wherein a cellular link module of the user equipment can receive the RRC control signaling from the cellular network when the user equipment is in an idle mode; and the WLAN AP performing channel switching within a predetermined time, the user equipment acquiring channel switch information by receiving the channel switch announcement request signaling, wherein the user equipment acquires the channel switch information from the cellular network base station by receiving the channel switch announcement request signaling from the cellular network base station, further wherein the user equipment follows the WLAN AP and performs channel switching. before a WLAN access point, AP, performs channel switching, the WLAN AP delivering channel switch announcement signaling to associated user equipments in a broadcast manner, and sending channel switch announcement request signaling to a cellular network base station that serves the associated user equipments, the characterized in that channel switch announcement request signaling comprises: a user equipment ID for the user equipment that cannot receive the channel switch announcement signaling as predicted by the WLAN AP, an ID of the WLAN AP, a channel switch mode of the WLAN AP, a channel before switching, a channel after switching, and a time for channel switching; the cellular network base station, after receiving the channel switch announcement request signaling, sending the channel switch announcement request signaling, by using radio resource control, RRC, control signaling, to a user equipment in an idle mode via a cellular link air interface, wherein a cellular link module of the user equipment can receive the RRC control signaling from the cellular network when the user equipment is in an idle mode; and the WLAN AP performing channel switching within a predetermined time, the user equipment acquiring channel switch information by receiving the channel switch announcement request signaling, wherein the user equipment acquires the channel switch information from the cellular network base station by receiving the channel switch announcement request signaling from the cellular network base station, further wherein the user equipment follows the WLAN AP and performs channel switching.