Abstract: In this paper, from the original measurement data of the thermal deformation of a paraboloid double-reflector antenna under the normal temperature, HT, and LT conditions, and based on the standard theories of the paraboloid fitting and the common-point conversion, we propose a new method to obtain the facial deformation of the mail reflector and the positional deformation of the sub reflector. The method is shown to be reliable for the prediction and the analysis of the on-board performance of the satellite double reflector antenna. The method may also be used for measuring and analyzing other satellite antennas with regard to their thermal deformation.