Abstract: Selective laser melting(SLM)technology can achieve high precision and rapid manufacturing of complex components,it has been widely used in the aerospace industry,however,it is inevitable that there will be defects inside the formed parts.For improving the SLM forming process of actual products and determining the acceptance conditions of product quality,the defect distribution of TA15 samples prepared by the same process as the actual product was studied by SEM,the results show that:there are mainly blowholes and non-fusion defects in the sample,samples with different thicknesses show the same distribution law,non-fusion defects are mainly distributed in the surface area of the sample,blowholes are mainly irregular and diffuse distribution,on the whole,the distribution of defects shows a certain aggregation trend.