Abstract: This paper reviews three kinds of terahertz (THz) radar cross section (RCS) measurement technologies, viz. microwave up-conversion, laser down-conversion and terahertz time-domain spectrum. Their characteristics like set-ups, specialties and applications are mainly introduced. We build a THz RCS measurement system with solid state components based on microwave up-conversion technology, and employ time-domain method based on the sweep and inverse synthetic aperture radar (ISAR) technologies to perform angle- and frequency-resolved RCS measurements on scale-model targets, then the 2D scattering image and RCS on targets are obtained.