Abstract: To reducing the operation costs of the mandrel pipe mill,and seek some new approaches to properly utilizing the metal material,a complex mandrel has been developed successfully by Tianjin Pipe (Group) Corporation by means of selecting proper welding material and heat treatment process,and adopting the build-up welding process to treat the surface of the 42CrMoA general-purpose alloy structural steel bar. The actual operation with the newly-developed mandrel shows that its operational effectiveness is equal to that of the H13 mandrel. Detailed here in the paper are the main aspects concerning the complex mandrel,covering the R & D activities,the performance and economic profit it has brought about as well as suggestions involving the recycling and quality improvement of the mandrel in the future.