Abstract: The forming quality, microstructures and corresponding forming defects in three-dimensional metal welding deposition are directly affected by the waiting time between layers because of the overlapping thermal cycles. Finite element models of single pass multilayer linear round-trip deposition based on SYSWELD solver were established. And experiments were conducted to verify the results. The results showed that the complex temperature field and thermal cycles of the welding deposition prototyping could be obtained accurately by numerical simulation method. As the layers increased, the heat accumulated gradually. Heat affected zone in the rear area of heat source enlarged constantly. Thus the waiting time between layers needed to be set. When the waiting time was greater than 30 s, the weld zone experienced a significant temperature cycle, and the forming quality was better. The microstructure was more uniform and fine with the increasement of the waiting time.