The invention discloses an ultra-precision motion system feedforward controller parameter tuning method. If the DC gain of a feedback controller is finite, a tracking error is proportional to the N-order derivative of a reference trajectory, that is, the tracking error and the N-order derivative of the reference trajectory have the same shape, the feedforward coefficient of the N-order derivativeis judged to be inaccurate, a bisection method is used to tune the feedforward coefficient of the N-order derivative until the shape of the tracking error is the same as the (N+1)-order derivative ofthe reference trajectory, and an accurate N-order derivative feedforward coefficient can be obtained; and if the DC gain of the feedback controller is infinite and only contains a first-order integral, the tracking error is proportional to the (N+1)-order derivative of the reference trajectory, the feedforward coefficient of the N-order derivative is judged to be inaccurate, the bisection method is used to tune the feedforward coefficient of the N-order derivative until the shape of the tracking error is the same as the (N+2)-order derivative of the reference trajectory, and an accurate N-order derivative feedforward coefficient can be obtained, and N is increased gradually with a step 1 from 2 until the tracking error meets requirements. The tracking errors in acceleration and deceleration regions can be greatly reduced, the building time is reduced, and the system yield is enhanced.