Abstract: The paper introduces the structure, automatic control system and site application of pipeline all-position automatic welder. This kind of welder is characterized by a high level automation and great convenience in operation. To meet the needs of construction of pipeline, a new PAW 2000 all-position automatic welder is developed. This welder is successfully put into operation in some domestic oil and gas pipelines. It is considered that this welder not only ensure the welding quality and enhance welding efficiency, but also greatly reduce labor intensity, suitable to the construction of long distance oil or gas pipeline. The process evaluation method of PAW 2000 all-position automatic welder is given and economic analysis result is also made.