Q345C steel is welded under two different pre-welding heating methods of traditional flame heating and ceramic sheet heating.The finite element analysis of the butt joint weldment by ABAQUS software is used to summarize the law of welding HERBATINT FF5 deformation and compare the welding quality under different pre-welding heating methods according to the residual stress and deformation trend of the welding joint weld.The results show that the main stress after welding is concentrated in the weld seam and the surrounding area.The residual stress Collections after welding after the heating and welding of the ceramic sheet is significantly less than the residual stress after the traditional flame heating welding, and the welding after the heating of the ceramic sheet can obtain better welding quality.