Due to the special service environment of LNG marine cryogenic valve, it is necessary to surface the cobalt-base alloys on the sealing surface. Through the process qualification of two kinds of materials and four kinds of specifications, one kind of GTAW surfacing welding process and four kinds of PTA surfacing welding processes are provided. By comparison, GTAW welding deformation is larger than PTA, and GTAW welding time-consumption is longer, but GTAW welding dilution rate is lower; the hardness test values in weld fusion zone of GTAW welding and PTA welding after welding are similar to that of welding material, and their chemical composition is not much different from that of welding material. This research is of the practical significance for realizing the domestic independent and mass production of LNG marine cryogenic valve.