Abstract: When turning a 20CrMnTi steel gear blank, it was found that there were spot defects on the surface. The causes of point defects were analyzed by macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination and other methods. The results show that when heating before hot forging, the refractory particles in the heating furnace adhered to the surface of the material, and these particles were squeezed into the steel during hot forging,thus forming point defects.