Abstract: The welding of safety end and pressurizer nozzle is the welding of dissimilar metals.This paper studies the effect of some factors（such as the choose of filling material,the performance of filling material,the characteristics of welding procedure of nickel-base alloy,joint type,qualification of welding procedure and production welding） on the quality of the weld.The study indicates that,the nickel-base alloy weld molten pool is viscous,and it is suggested to agitate the molten pool gently during the welding;the welding of nickel-base alloy may generate hot cracks and gas cavity easily,so the chemical constitution of the nickel-base alloy filling materials shall be controlled strictly.