Abstract: Inverse synthetic aperture radar (ISAR) can image moving targets such as aircrafts, ships, satellites and space debris, and is of great importance in military and civil applications. ISAR 3D imaging can overcome the problems of geometric distortion, difficult azimuthal calibration and unknown image projection plane in traditional 2D imaging, and is conducive to the classification and identification of targets, which is one of the important development trends of ISAR technology. This paper introduces the different systems of single-antenna ISAR, interferometric ISAR and array ISAR for 3D imaging. On the basis of introducing the mechanism of 3D imaging in different regimes of ISAR, the current research status of various regimes is summarized and the future development direction is analyzed.