Quartz crystal is acknowledged as one of suitable material for fabricating some specific MEMS devices as its excellent properties can complement those of silicon. This study mainly aims at establishing a user-friendly 3D etching simulator for quartz to better guide etching process and shorten developing period of quartz MEMS devices. We focus on etching simulation of 3D concave vertex of AT-cut wafer with improved database processing method and simulation method based on hull construction. The consistency between simulation result and experiment result shows that our method and process can well predict the 3D anisotropic etching profile of concave vertexes for AT-cut wafer.