Abstract: To determine the feeds phase center for distorted reflector antennas, the optimization model is given. The proposed model bases itself on the expression between feeds phase center of distorted reflector antennas and its far-field pattern. The optimal feeds phase center of reflector antennas existing reflector surface errors can be worked out to obtain the minimal gain loss by this model. Finally, as an example, a practical calculation is carried out for a 8m reflector antenna. Only considering the gravity loading cases, the optimal feeds phase centers can be obtained in different elevation cases. The numerical results show that the gain loss of the given model is less than the one of best fit paraboloid.