Abstract: The metallurgical defects, such as pores, unmelted powders, and cracks, always appear in the processed components prepared by selective laser melting (SLM). The numerous researches focus on minimizing the inherent defects, but there are few studies on the effect of process parameters on these defects. The influence of process parameters on the relative density, surface roughness, and tensile properties of the selective laser melted Ti6Al4V were studied in this paper. The results show that, the low laser power, high scanning speed, and high layer thickness cause the insufficient melting and the balling effects. In the case of Ti6Al4V, the optimized process parameters are considered as the laser power of 200 W, scanning speed of 500 mm/s, layer thickness 30 μm, and hatch distance of 105 μm, with which the processed sample presents the ultimate tensile strength as 1077 MPa and the yield strength as 907 MPa.