Abstract: 　　Double wire submerged arc welding, as an efficient welding method, has been widely used in enterprises. In order to further understand the differences between double wire submerged arc welding and single wire submerged arc welding, it is necessary to conduct research on the microstructure and properties of single and double wire submerged arc welding joint. A welding process evaluation test was conducted for single wire and double wire submerged arc welding of 400MPa low carbon steel flatbutt X-groove. Mechanical properties tests such as tensile, bending, and impact were carried out on the welded joints, and microscopic metallographic observation and hardness testing methods were used to analyze the microstructure,grain size, and hardness of the joints. The results show that the tensile, bending, and impact testing results of the 400MPa low carbon steel single and double wire submerged arc welding joint meet the relevant standard requirements, and the mechanical properties are good; Double wire submerged arc welding has slightly higher strength and hardness than single wire submerged arc welding, but slightly lower impact toughness; Compared to single wire submerged arc welding, double wire submerged arc welding has coarser grains in the heat affected zone between the base metal and the weld seam, and a more pronounced cellular dendritic structure in the weld seam area.