AlSi10Mg samples were formed by selective laser melting (SLM) process, the microstructure and mechanical properties of the samples were studied. The AlSi10Mg sample was printed by AFSM260 selective laser melting machine produced by a company, the sample was analyzed by using microhardness tester, optical microscope, scanning electron microscope and XRD diffractometer, and its micro hardness, structure morphology, element distribution and phase composition were obtained.The directional growth of the eutectic structure caused by the unique forming method of SLM makes the anisotropic microstructure of the sample in the horizontal and vertical directions,but the microstructure on the same section presents a gradient structure from the boundary of the molten pool to the inside,which can be divided into three regions, namely, coarsegrained zone, heataffected zone, finegrained zone.The α-Al matrix size, average eutectic Si width and eutectic structure content in the transverse and vertical sections of each zone show a downward trend.The hardness of the sample is significantly larger than that of the conventional ascast sample,but the transverse and longitudinal sections are not much different.The SLM-formed AlSi10Mg sample has excellent hardness properties and a small formed microstructure, which is mainly due to the high cooling rate of SLM forming.