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(R₁/R₂) and wheel center locus. Furthermore, the critical grinding wheel radius(R₁) can be calculated from work-piece radius(R₂) and inclined angle(θ=-45°). These achievements could be applied to calculate CNC data in ultra-precision grinding and give insight for wheel wear and compensation grinding.