Abstract: The single pass, block and tensile sample forming tests of 316L stainless steel powder were carried out by using high power selective laser melting and different layer thickness (150, 200, 250 μm). The single pass morphology, density and section structure of the block and the tensile property were studied. The results show that the average melting width increases with the increase of the layer thickness.For the same layer thickness, the longer the exposure time, the bigger the fusion width.With the increase of layer thickness, the exposure time of single channel needed for stable forming increases.Droplet splashing occurs under the three layer thicknesses, and the degree of droplet splashing increases with the increase of layer thickness. For the same layer thickness, the longer the exposure time, the larger the splashed particles. Under the same conditions, the forming effect gradually deteriorates with the increase of the layer thickness. When the layer thickness is 150 μm, the density is the maximum of 99.9%, and the mechanical properties with 200 μm of layer thickness are the best.At 250 μm of layer thickness, the grain size becomes bigger, the density is smaller, and the mechanical properties are worse. The thickness of the powder layer cannot be increased infinitely, and it needs to be within a reasonable parameter range to ensure the forming effect.