Small layer thickness is commonly used for printing in the selective laser melting (SLM) process to improve the forming quality of the parts. However, it has a negative impact on production efficiency and is not commercially viable. To solve the contradiction between good forming quality and high SLM production efficiency, 316L stainless steel specimens with different powder layer thicknesses were prepared using optimizing process parameters. The technological parameter of the relative density, roughness, mechanical properties, and microstructure of the formed parts was studied under different powder layer thicknesses. When the forming conditions of three layer thicknesses (30 μm, 45 μm, and 60 μm) are compared, it is discovered that the layer thickness has little effect on the relative density of SLM samples under the optimized process window condition. Moreover, the relative density can reach more than 99.90% under different powder layer thicknesses, and there are no obvious defects in the microstructure. The dimensional accuracy, surface roughness, and mechanical properties of the samples are mainly affected by the layer thickness. The tensile strength gradually increases as the layer thickness increases, while the dimensional accuracy and roughness decrease. The forming efficiency of 60 μm powder thickness is increased by 35. 71% compared with 30 μm powder thickness.