Quick-point grinding is used to machine the round surface with super abrasive wheel at high grinding speed. Because it is point contact between the grinding wheel and the workpiece due to the point grinding angles in the process, the grinding model is different from the conventional cylindrical grinding in theory. Especially, the edge contact width between the wheel and the workpiece is not always equal to the thickness of the wheel, but rests with the depth of cut and the grinding angles greatly. The depth of cut has the effects on the micro-geometric properties especially the ground surface roughness by means of the variations of the edge contact width, the grinding force and heat in the process. Based on the theoretical studies on the surface roughness, the quick-point grinding experiments and the measures for the surface roughness were performed at different depth of cut. The effective mechanism of the depth of cut on the ground surface roughness was analyzed deeply. Some conclusions to influence surface roughness were also gained.