Abstract: Three kinds of 316L stainless steel flux cored wire with different Cr content were designed to investigate the effect of heat treatment on the microstructure transformation and properties of surfacing corrosion resistant layer in this paper. The results show that the increasing of ferrite number, heat treatment temperature and holding time will reduce the ferrite content in the surfacing layer and increase the precipitation of σ phase, resulting in the increase of strength and plasticity of the surfacing layer, and lead to bending cracking phenomenon. With the decrease of ferrite number, the corrosion resistance of heat treatment surfacing layer is improved. However, the corrosion resistant layers with three different ferrite numbers can be detected by the intergranular corrosion E method. Based on the optimized mechanical properties and corrosion resistance of corrosion resistant layer, the design principle of alloy composition of 316L stainless steel flux-cored welding wire for surfacing corrosion resistant layer is proposed. By controlling the content of alloying elements, the range of ferrite number in weld is kept between 5 and 8.