Abstract: In order to investigate the mechanical properties of 316L stainless steel prepared by selective laser melting, this study fabricated three types of 316L stainless steel samples through SLM, hot rolling, and solution treatment after hot rolling. The microstructure of the samples was observed, and their mechanical properties were studied and compared using tensile, three-point bending, and impact tests. The results showed that the tensile strength and bending strength of SLM samples were significantly superior to those of homogeneous materials formed by traditional methods, but their plasticity and toughness were poor. On the one hand, due to the rapid melting and cooling during SLM forming, the grains were very small and densely arranged, as well as the deformation resistance at the fusion interface, resulting in a significant increase in the strength of the material. On the other hand, it is believed that a non-equilibrium microstructure is formed during the forming process, and the shrinkage and expansion deformation trends of different parts inside the sample are inconsistent. Residual stresses inside are inevitable, resulting in low plasticity and decreased elongation. Due to the influence of hot work hardening and the recovery, recrystallization, and growth of grains caused by heating, the internal stress is reduced, resulting in slightly higher mechanical properties in the hot-rolled state than in the solid solution state. The fracture morphology of the tensile and impact tests shows that the SLM sample exhibits brittle fracture characteristics, while both the hot-rolled and solid solution states show obvious ductile fracture characteristics, and the solid solution state has relatively fewer toughness dimples but larger size, with better plasticity.