Aiming at the defect of enfold and the shortage of material around web in the forming process of necking for drill pipe joint, the finite element software Derorm-3D was employed to simulate the whole process and the shape factors of necking. The results show that the defect is mainly caused by complex metal flow at the bottom of formed parts when backward extrusion and necking at the same time. Through the analysis of forming factors including punch shape, matrix cavity and friction coefficient，the solutions were determined, such as shortening the length of the punch, increasing the punch diameter, changing cone angle of the concave die, increasing the table at the bottom of concave die and reducing the friction coefficient . Finally, the qualified workpiece is produced.