Abstract: An iteration method for determination of conversion points at arbitrary interfaces is advanced in this paper. This method can calculate the locations of conversion points with very high precision for any travel time of converted waves, generally through not more than three iterations, given the shot-to-receiver distance, the S-wave and P-wave velocities, and the dip angle of interface are known. The method is simple, efficient and stable. It can not only be applied to CCP gathering, but also can be applied to converted wave velocity analysis and NMO.