In order to meet the high requirements of tank welding technology, according to the structural characteristics and use environment of low-pressure tank, the welding method, welding process parameters and welding materials suitable for low-pressure tank are studied, and a reasonable welding process is formulated. The mechanical performance test, metallographic test and nondestructive testing are carried out to evaluate the welding process, so as to verify the correctness and feasibility of the designed welding process. According to the problems existing in welding process evaluation, the process was improved.