The effects of different focal spot diameters and powder particle sizes on the surface morphology, surface roughness, density, hardness, tensile strength, elongation, and microstructure of 316L stainless steel selective laser melting (SLM) forming parts were investigated to obtain higher quality 316L stainless steel SLM forming parts. The findings reveal that the particle size of the powder has a considerable impact on the SLM forming quality. Using 0-25 μm particles yielded superior surface roughness and elongation, which were 3.27 μm and 50.71%, respectively. The powders with 15-53 μm particle size had 238.82 HV and 748.16 MPa hardness and tensile strength, respectively. The combination of focal spot diameter and powder particle size has an impact on SLM forming quality. Surface roughness, hardness, tensile strength, and elongation of SLM with different powder particle sizes differed more from those of SLM with a focal spot diameter of 25 μm when compared to those of SLM with a focal spot diameter of 50 μm.