Abstract: In view of the problems when grinding optical glass, such as the difficulty in machining, the poor surface quality of the workpiece and the serious internal damage of the workpiece, an ultrasonic vibration assisted machining method is proposed to study the engraving of BK7 glass.Firstly, a constitutive model of BK7 glass material is established by using the finite element software.Then the damage mechanism of the glass matrix after ultrasonic vibration of diamond abrasive is analyzed.Finally, an experiment is designed to study the influence of ultrasonic vibration power, speed and depth on the subsurface crack.The results show that the maximum depth of subsurface crack in ultrasonic etching is 19.7% lower than that in ordinary etching.With the increase of etching speed, the maximum depth of subsurface crack at the bottom of the groove increases gradually.With the increase of groove cutting depth, the maximum depth of subsurface crack increases gradually as a whole, and obvious classification occurs.