The invention discloses a fluorine plastic pipe and fixing plate connecting device for a heat exchanger. One end of a fluorine plastic pipe is fixed in a fixing hole. A threaded hole is further formedin a fixing plate. An expansion connecting pipe is further arranged in the fluorine plastic pipe in an inserting mode and is in a conic shape. The threaded hole is internally provided with a pressingnut abutting against the end part of the expansion connecting pipe. A through hole communicating with the expansion connecting pipe is formed in the pressing nut. A connecting method sequentially comprises the following steps that one end of the fluorine plastic pipe penetrates from the lower portion of the fixing hole, a rear flanging forms a convex brim to be tightly attached to the bottom surface of the threaded hole; and the small head of the expansion connecting pipe is inserted into the fluorine plastic pipe from the upper portion, the pressing nut is screwed into the threaded hole, andthe bottom surface of the pressing nut abuts against the top surface of the expansion connecting pipe. The fluorine plastic pipe and fixing plate connecting device for the heat exchanger has the advantages that the outer wall of the fluorine plastic pipe is tightly attached to the inner wall of the fixing hole, positioning and sealing of the fluorine plastic pipe are achieved, and the pressing nut is used to abut against the expansion connecting pipe, so that tension force of the expansion connecting pipe on the fluorine plastic pipe is kept to be unchanged, a connecting mode is simple in machining, connecting is reliable, the machining cost is low, and assembly requirements are low.