Abstract: In this paper, through the research on the effect of FCAW welding process measures, such as preheating temperature, inter-pass temperature and girth weld pass number, it was found that welding process measures such as preheating, inter-pass temperature and multi-layer and multi-pass welding were adopted to improve the microstructure of weld and heat affected zone and prevent coarse grains, and then to im-prove bending performance and low temperature impact toughness of girth welded joints. At the same time, there was a reasonable range of preheating temperature, inter-pass temperature and the optimal number of weld passes with different wall thicknesses, which should be determined through welding process qualification to ensure the stability of the comprehensive mechanical properties of girth welded joint.