The invention discloses a wireless fixed terminal capable of switching talk lines automatically and a switching method. The terminal comprises a wireless communication module, a subscriber line interface card (SLIC), a switch control circuit and a public switched telephone network (PSTN) interface circuit, wherein, the wireless communication module is used for detecting whether a wireless networkside is called or not at a real time, and sending a channel switch control instruction to the switch control circuit based on the interface connection state of a current circumscribed telephone set and the detection results reported by calling detection result or the PSTN interface circuit; the SLIC is used for carrying out two wire-four wire transformation on a voice signal alternated between the wireless communication module and the circumscribed telephone set; the switch control circuit is used for finishing the connection control of the SLIC or the PSTN interface circuit and the circumscribed telephone set according to the channel switch control instruction; the PSTN interface circuit is used for realizing detection on the line status of a wired network side and calling and the pickupand hangup state of the circumscribed telephone set, and reporting the detection results to the wireless communication module. The invention can realize voice call service respectively from two lines, and is used conveniently and economically.