Abstract: With the first grid connection of Hualong No. 1, marking that China has become one of the major nuclear power countries, in view of the large amount of welding engineering and high welding cost of small-size pipes below 10 inches in various nuclear power projects, and the traditional welding methods can no longer meet the current status quo of nuclear power construction and safety, so our company independently developed a set of open full-position automatic welding equipment (equipment model: 23HY-Arc400-P/K) dedicated to small-size pipes to meet the construction needs of nuclear power projects and reduce construction costs and cycles. This paper takes the open full-position automatic welding equipment as the starting point, introduces the demand for automatic welding equipment for nuclear power in China, systematically expounds the composition of the equipment and its unique partition welding function, and introduces the welding process test verification and field application, which provides a reference for the subsequent development and promotion of new products.