Welding is very important in the manufacturing process of tower crane, which can directly affect the safety and reliability of the whole tower crane. This paper takes the standard section of tower crane as the research object, and calculates the thermodynamics by analyzing the welding process between the support rod and the reinforcement rod. The transient temperature field and stress field at different time were obtained by thermo-mechanical coupling method. In addition, metallographic analysis was carried out for different regions of the weld. It is important to deduce the mechanical properties of the weld for improving the performance of the weld.