In this paper, we discuss the method for measuring radar cross section (RCS) based on the Range-Doppler Imaging. In this method, the measured targets are rotated and the Doppler frequencies caused by each scattering element along the targets are analyzed by FFT. Using this method, each scattered power along the flighting model is measured. It is found that each part RCS of flighting model can be measured and its RCS of a main wing (about 46dB·cm²) is greater than its of body (about 20-30dB·cm²).