Hair pin motor is widely used in new energy vehicles as it has high slot full rate, good heat dissipation, small volume and good cost performance. But its winding is small size electromagnetic wire normally. Compared with small size wire motors, large size wire motors supply more power. The structure and forming difficulties of the big size hair pin enamel membrane insulated winding are described in detail, and the problems appearing during the forming process of the U shaped section and the end by punch forming and extrusion forming techniques are analyzed. The forming technique is optimized in terms of process, mould, wire and operation, and satisfactory winding forming results are obtained.