In this paper, the CSAR (circular synthetic aperture radar) technique is introduced firstly. The principle of CSAR 3D (three dimensional) imaging and the spatial wavenumber support are analyzed and the 3D resolution is discussed secondly. Secondly, Ku band fully-polarimetric CSAR human body imaging experiments are performed, and the experimental data is processed by a fast 3D backprojection algorithm, the corresponding amplitude images are shown. Finally, the future experiments for human body imaging are discussed.