The invention relates to an elliptic arc interpolation method, which comprises the following steps of: 1, expressing an elliptic track where an elliptic arc is located in a parameter form of a standard elliptic equation; 2, calculating a stepping angle delta theta between a current interpolation point Pi (xi, yi) and a next interpolation point Pi+1 (xi+1, yi+1); 3, calculating a coordinate of thenext interpolation point Pi+1 (xi+1, yi+1) according to the coordinate of the current interpolation point Pi (xi, yi); and 4, making interpolation reach an end point of the elliptic arc if the current interpolation point Pi (xi, yi) does not exceed the end point of the elliptic arc and the next interpolation point Pi+1 (xi+1, yi+1) just reaches or exceeds the end point of the elliptic arc, and finishing interpolation process; otherwise, making the interpolation not reach the end point of the elliptic arc, carrying out the interpolation by using the Pi+1 (xi+1, yi+1) as a new current interpolation point, and then returning to the step 2. The elliptic arc interpolation method is applied to the interpolation of anticlockwise and clockwise elliptic arcs which have any start points and any endpoints and the whole ellipse, so that calculation of the interpolation points is simple and fast, the accuracy of the track is high, and discrimination of the end point is fast and correct.