Forming process scheme of magnetron exhaust pipe cold extrusion was analyzed and carried out according to extrusion theory. The process was simulated using the Deform-3D. The forming law in the cold extrusion process of magnetron exhaust pipe and the optimization of parameters were studied using the combine method of theoretical analysis, numerical simulation and experiment research. After the regression analysis and orthogonal test, the optimized parameters of the die structure are as follows: punch fillet r1=0.8 mm, punch round r2=0.8 mm, recess fillet r3=0.8 mm, recess round  r4=0.8 mm; and process parameters are as follows: straight pipe length x1=30 mm, cone angle of the billet x2=120°, friction factor x3=0.1, extrusion speed x4=180 mm·s^-1. The results show that cold extrusion is reasonable for forming thin-walled bar.