Circular SAR has several attractive features, such as full-aspect observation, high resolution, and 3D target reconstruction capability, thus it has important potential in fine feature description of typical targets. However, the 3D reconstruction capability relies on the scattering persistence of the target. For target with a highly directive scattering property, the resolution in the direction perpendicular to the instantaneous slant plane is very low compared to the range and azimuth resolutions, and the 3D structure of target can hardly be obtained. In this paper, an Interferometric Circular SAR (InCSAR) method is proposed to reconstruct the full-aspect 3D structure of typical targets. InCSAR uses two sensors with a small incident angle difference to collect data in a circular trajectory. The method proposed in this paper calculates the interferometric phase difference (IPD) of the image pair at equally spaced height slices, and mask the original image with an IPD threshold. The main principle is that when a scatterer is imaged at a wrong height, the image pair has an offset, which results in a nonzero IPD, and only when the scatterer is correctly imaged at its true height, the IPD is near zero. The IPD threshold is used to retain scatterers that is correctly imaged at the right height, and meanwhile eliminate scatterers that is imaged at a wrong height, thus the 3D target structure can be retrieved. The proposed method is validated by real data processing, both the data collected in the microwave chamber and the GOTCHA airborne data.