Abstract: Aiming at solving the difficulties in grinding the high accuracy conical surfaces of the hydrostatic seal rings used in the reactor coolant pumps, a mathmatical model of grinding with the end face of a cup wheel was established and an implementation strategy of dividing the form error into two parts named the inclined angle error and taper error was proposed to calculate the value range of the pitch angle and the tilt angle. Taking one helium light band as the evaluation criteria, it is found that the values of the pitch angle and tilt angle could be selected in a large range and high accuracy grinding of the conical surfaces could be achieved by coarse adjustment for one of the angles and accurate adjustment for the other one. Since the tilt angle was more sensitive to the form accuracy than the pitch angle, the adjustment difficulty could be reduced and the adjustment accuracy could be improved when the tilt angle was adjusted at first. Two groups of the pitch angle and tilt angle were chosen in the proposed implementation strategy to grind the conical surfaces of the seal rings and the measurement results indicate that the form error and the surface roughness fulfilled the designed accuracy requirements.