To improve the machining efficiency of fused silica optical elements with large diameters, this paper presents a method for heat-assisted ductile ultra-precision grinding of the fused silica. The mechanism of heat-assisted ductile grinding for the fused silica was analyzed, and the effect of different grinding depths on the highest temperature rise on the surface of the grinding zone was investigated by theoretical inference. The fused silica was ground in dry method by a high temperature resistant ceramic bond Cubic Boron Nitride(CBN) wheel and the high efficiency ductile grinding of fused silica was realized by using grinding heat to improve the mechanical properties of fused silica in the grinding zone. Through the grinding experiment, the effect of different grinding depths on the surface roughness(Ra) and sub-surface damage depth of fused silica was investigated. The experiment results show that the Ra and sub-surface damage depth are reduced with the increase of grinding depth. When the grinding depth is greater than the crack depth(5 μm) by coarse grinding, smooth and no crack surface of ductile grinding with the Ra 0.07 μm can be achieved. The mechanism of wheel wear was studied by a scanning electron microscope. The results show that the wear mechanism of ceramic bond CBN wheel ductile grinding of the fused silica is grain flatted, which provides the basis for researching a new type of ceramic bond CBN grinding wheel for dry grinding of the fused silica.