Abstract: In order to improve the grinding quality of fused silica optics and reduce the depth of subsurface defect (SSD), the experiment of grinding fused silica and theoretical analysis were carried out by parallel diamond grinding wheels with straight edge and circular edge. The stress concentration on the straight edge of wheel was the main cause of deep defects like continuous white line, whose depth was about 22 μm. To relieve the stress concentration, a combined cross section profile with circular edges was designed. The propounded dressing method was verified by wheel dressing experiment. After grinding using the latter wheel, the deep defect was constrained remarkably, and the depth of SSD was below 2.5 μm. The purpose of low defect grinding of fused silica optics was achieved.