Abstract: The insitu 3D printing of lunar regolith（additive manufacturing）can realize the in-situ construction of the lunar base and the insitu manufacturing of key components，and can greatly reduce the cost and risk of the lunar exploration mission.A selective laser melting lunar regolith simulant experiment system was built to carry out single-track molding experiments to explore the effect of the first powder layer thickness on the densification of the sample，while the width and depth of each track were measured.The results show that the width of the single-track decreases with increasing scanning speed until the width is almost constant.At the same laser power，the single-track depth becomes deeper as the first powder layer thickness increases.The singletrack depth increases and then decreases with the increase in scanning speed.The density of a single-track can reach 2.5g/cm3，and the relative density is 86%.As the scanning speed increases，the density of single-track for different layer thicknesses is stabilized at 1.7g/cm3.When the first layer of powder is thinner，the density of single-track is also slightly higher than other layer thicknesses.

Key words: in-situ resource utilization（ISRU）, lunar regolith simulant, selective laser melting（SLM）, powder layer thickness, sunlight, laser power