The utility model relates to a pipe joint used in chemical industry, particularly a corrosion-prevention steel plastics combined loose joint, which is characterized in that the existing steel plastics combined pipe is utilized, the inner wall of the terminal port of one mutual connecting end is processed to be an inclined plane, a plastic seal liner with a rubber-ring gasket and a terminal port with an inclined plane cooperates with the pipe, and fastened by a set locating device. The utility model not only can be connected with the steel plastics combined pipes in random length, but also has the properties of self-sealing and anticorrosion.