In this paper,the Alsi10Mg alloy samples were prepared based on the selective laser melting (sLM) techniQue,and the effect of linear energy density and volumetric energy density on relative density and pore defects were investigated.The for- mation mechanism of defects were revealed by analyzing of defect micro structure and melt pool characteristics.The results show that the relative density of different samples is obviously different for the same linear/volumetric energy density,and the relative density difference among different samples is significantly reduced by using linear energy density cooperating with vol- ume energy density.The relative density of over 99% is obtained when linear energy density is from 0.12 to 0.28 J/mm and volume energy density is from 30 to 70J/mm3.In addition,low linear and volumetric energy densities result in irregular lack- of-fusion defects that traverse multiple melt pool layers,while high linear energy density leads to the formation of circular key- hole defects with large pore sizes located at the base of the melt pool.