Production method of composite bimetal pipe

A production method of composite bimetal pipe includes the following steps: making surface treatment of internal pipe and external pipe: inserting internal pipe into external pipe, tight fitting to form composite pipe blank; seating the two ends of the said pipe blank with air and liquid in the internal pipe, and sealing the gap between the internal pipe and the external pipe, heating and diffusion annealing so as to obtain the invented product. Its production process is simple, and is applicable to various anticorrosion pipes.