Selective laser melting (SLM) is an additive manufacturing technology to directly form complex metal parts. It has been demonstrated in aerospace and other fields. In the SLM single-pass formation process, the SLM layer distribution was modeled here via the discrete element method model (particle contact force model and particle motion equation). A dynamic behavior model of molten pool based on the particle scale was also established. The governing equations considered the influence of thermodynamic factors such as Marangoni effect, gasification recoil, and gasification heat dissipation. The laser energy model used a Gaussian heat source based on interface tracking. To study the influence of laying powder on SLM single-pass formation, the corresponding simulations were performed from three aspects: particle size distribution, powder bed tightness, and lamination thickness. To obtain a good formation zone in the actual SLM process, metal powder with a smaller average particle size should be used on the basis of saving money, and the proportion of large-sized particles in the powder should be minimized. A higher powder bed tightness is needed on the basis of ensuring a good connection with the substrate or the previous printed layer. Finally, a larger lamination thickness should be used on the basis of ensuring that the powder bed is sufficiently melted in the formation zone. This paper is expected to provide some guidance for the actual SLM laying powder process. (C) 2019 Elsevier Ltd. All rights reserved.