By means of selective analysis for round hole specimen, the influences of laser power, scanning line angle and number of contour scans on the forming quality of overhanging round holes are investigated. The results show that, the laser power has a significant effect on the forming quality of round holes. With the increase of laser power, the roundness of round holes increases and the dimensional accuracy decreases. At the same time, there are many thin and long melt pools on the overhanging surface, and part of them are fractured into spherical droplets; the overhanging surface quality is better when the scanning line direction is parallel to the edge lines of the overhanging surface, but there occurs a serious collapse on the top of round holes and near to the horizontal overhanging surface. Within the setting number of scans, the increase of the number of contour scans can reduce the surface roughness of the overhanging surfaces and optimize the surface quality.