The INCONEL 625 alloy surfacing layers are obtained by four different welding methods:CO,2, gas shielded flux cored wire arc surfacing,electrode arc surfacing, double-layer submerged arc surfacing with band-electrode and double-layer electroslag surfacing with band-electrode. A series of physical and chemical properties of this alloy surfacing layer are analyzed and compared.The rationality of each welding method is verified by comparison. Combining with the results of physical and chemical properties,the surfacing of the inner wall of PTA crystallizer is performed. And the productive task is completed on time and guarantees both quality and quantity.