An installation structure and an installation method of a plug-in switch tube is disclosed in the present invention, the installation structure comprises, a PCB board, a plug-in switch tube fixed on said PCB board, and a housing matching said PCB board and said plug-in switch tube, wherein the lower end surface of said housing is provided with a cooling liquid flow channel, and said plug-in switch tube is pressed against the side wall of the cooling liquid flow channel by an elastic pressing-piece. The installation structure according to the present invention has the advantages of small volume, excellent heat dissipation effect, simple assembly, low cost and light weight.