This paper presents the geometrical analysis of an inclined ultra-precision grinding technology using simulations about grinding point locus for micro lens manufacturing. Simulation results show the relationship between radius ratios ($R_1/R_2$) and wheel center locus. Furthermore, the critical grinding wheel radius ($R_1$) can be calculated from work-piece radius ($R_2$) and inclined angle ($ heta=-45^{circ}$). These achievements could be applied to calculate CNC data in ultra-precision grinding and give insight for wheel wear and compensation grinding.