Abstract: A335 P22 chromium-molybdenum alloy steel is a 2.25Cr-1Mo high-temperature resistant pearlite heatresistant alloy steel, which has good plasticity, high temperature resistance, high pressure resistance, corrosion resistance, wear resistance and other special physical and chemical properties. The disadvantage is that it has a tendency to harden and reheat cracks in the welding process. In this paper, the characteristics of A335 P22chromium-silver alloy steel with large wall thickness are discussed to discuss more reasonable and applicable welding processes and control methods to ensure excellent welding quality.