Abstract: In order to study the influence of different scanning characteristic parameters on the surface morphology of selective laser melting (SLM), 316L stainless steel powder was taken as an example to carry out the single-layer and double-track numerical simulation at the mesoscopic scale. Based on the Discrete Element Method, the numerical model of powder bed is established. The Volume of Fluid method is used to calculate the melting, flow and solidification process of heated powder in powder bed. Considering the three scanning characteristic parameters of laser power, scanning speed and scanning spacing, the orthogonal experiment was designed and carried out to study the influence of selected scanning characteristic parameters on the tracks morphology on the surface of the formed part was studied from the two aspects of the tracks morphology and the tracks width.The effectiveness of numerical simulation was verified by actual printing and morphology observation experiments. The results show that in the range of linear energy density of 313 ~ 500 J/m and scanning interval of 50 ~ 90 μm, the morphology of melting tracks with smooth continuous local defects can be obtained, and the parameter combination in this interval is linearly corresponding in turn. In terms of the influence on the integrity of the weld morphology, scanning speed > scanning spacing > laser power.