Abstract: In order to study the influence of process parameters on the quality of 304L stainless steel by laser selective melting, the effects of laser power, scanning distance and scanning speed on the relative density and hardness of 304L stainless steel were studied by single factor experiment combined with orthogonal experiment method. The optimal process parameters of 304L stainless steel were obtained, and the microstructure and mechanical properties of the formed samples were characterized. The results show that when the laser power is 190 W, the scanning distance is 0.09 mm, and the scanning speed is 800 mm/s, the hardness of the sample is 75 HRB, the relative density is 99.24%, and the forming quality is the best. The scale-like microstructure is uniform and dense with few pores, the boundary of the molten pool is fine, and the grain orientation is basically random, and some of the coarse columnar crystals in the molten pool have a certain preference; the microstructure is mainly composed of austenite. The mechanical properties of the sample have obvious anisotropy, the tensile fracture has obvious necking, and the fracture form is ductile fracture.