Abstract: Aiming at the problem of low life of electrode cap during spot welding of atmosphere corrosion resistant steel coated plates for railway vehicle, the CuCrZr electrode caps with deep cryogenic treatment（DCT） and non-DCT were used for life test. The diameter change of electrode cap end face and joint quality were observed, the morphology, microstructure and hardness distribution of the failed electrode cap were analyzed. The results indicate that during spot welding of atmosphere corrosion resistant steel coated plate, the main failure mode of the CuCrZr electrode cap is the rapid increase of section size caused by plastic deformation, the life of CuCrZr electrode cap is increased from 90 to 180 points by DCT. The reason for life improvement is that DCT improves the conductive and thermal properties of CuCrZr, reduces the heat production of the electrode cap, dissipates heat quickly, reduces the overheating degree of the contact surface between the electrode cap and the coating, and thus slows down the speed of adhesion and plastic deformation.