Jig Grinder with superstructure fabricated by granite, which is well-known by its excellent damping, low heat conductivity, rust-proof, and corrosion resistance, is capable of stabilizing the machine accuracy and enhancing the roughness on workpiece. Stiffness and accuracy is also enhanced with the motors on three axis(X,Y,W) direct-driven design transmission. C1 grade ballscrew was adopted, pre-tension by 3°c in temperature increment, which is effectively upgrading stiffness and preventing from deformation during operation.