High precision CNC vertical grinder can be used for grinding of outer diameter, inner diameter and surface. According to the shape of the work piece, all three works can be carried out in one time. When this situation is possible, the error caused by multiple loading is avoided. The roundness between the inner diameter and the outer diameter, and the perpendicularity between the inner diameter and the outer diameter and the surface can be maintained more. Because the work piece and grinding spindle are vertical, there is actually no bending problem to be solved. This structure eliminates the sagging around the horizontal grinding table, reduces the movement resistance and saves energy consumption. The grinding and polishing of the processed work piece can be carried out on the same equipment, so that the operator can observe or check the grinding status at any time. On a vertical grinder, the work piece is mounted vertically in a chuck. On a horizontal grinder, the clamping force must be such that the work piece does not fall outside the chuck. The work piece clamped vertically only needs enough clamping force to resist the grinding force. Gravity is beneficial to the grinding process rather than hindering it. Since only a small clamping force is needed to fix the work piece on the vertical grinder, the deformation of the work piece may be less. This reduces the chance of roundness error.