Abstract: In order to reduce the clutter in near-field electromagnetic scattering measurement, a clutter filtering method in height dimension based on InSAR principle was proposed in this paper. Firstly, two radar two-dimensional images of the target are obtained by twice linear scanning of the antenna at different heights. Then, the amplitude and phase of scattering centers were extracted from the radar images data, and the height of the scattering center can be calculated by using some information, including the phase difference of the scattering center and antenna height between the two measurements. Afterwards, according to the target height range, the filter in height dimension was set to reduce clutter outside the target height range. Finally, the RCS of the target was constructed after filtering so as to reduce the clutter and improve the accuracy of RCS data. The result of simulation demonstrates that the mean RCS error is reduced to within 1 dB with applying the proposed method. And the scattering centers of an aircraft model are accurately extracted from a strong clutter experiment environment, which has the equivalent scattering intensity with the target.