Using the welding assembly finite element software, PAM-ASSEMBLY, we performed a dynamic simulation of Q345D low alloy high strength steel deformation under different welding sequences. A post processing module was used to gain welding deformation nephograms at different times under different welding sequences. The welding sequence of program 5 reduced the welding deformation by 11.95% compared to program 2, which suggests that reasonable arrangement and assemblage of welding sequence can effectively reduce welding deformation. The welding sequence of program 5 resulted in the smallest amount of welding deformation, which suggests that simultaneous welding during actual production is optimal. The results may serve as a guide for actual production and provide a reference to ultimately improve the weld-ability of Q345D low alloy high strength steel.