To reduce work-piece deformation and prevent cracking,a new idea of substrate partition preheating is proposed. Substrate forming area and near forming area were respectively preheated through partition preheating device,and the stress of work-piece was actively controlled and reduced base on thermal stretching effect. A numerical simulation model of 3D temperature field for single-pass and multi-layer laser deposition shaping process was established through the birth-and-death elements of ANSYS. Change rules of forming process temperature field and temperature gradient were studied,when substrate forming area and near forming area were respectively applied different preheating temperature and formed different preheating temperature difference between two areas (preheating temperature difference are 100 ℃,200 ℃,300 ℃). Compared with the substrate whole preheating mode,the process temperature gradient is more stable under substrate partition preheating mode,and it is helpful to reduce the thermal stress. Analysis results will provide guidance for the design of partition preheating device and optimal selection of the preheating temperature.