Abstract: Terahertz inverse synthetic aperture radar (THz-ISAR) works at high frequency band with short wavelength and large bandwidth. Compared to ISAR operated in microwave band, THz-ISAR is more susceptible to the phase error which will cause the spread and shift of range profiles, thus affect the quality of the two-dimensional (2-D) high resolution image. Based on detailed analysis of the echo model, a method of second order phase error compensation was proposed based on minimizing the entropy of range profiles through enlightened search. In the meantime, another method based on range autofocusing was utilized to compensate the third or higher order phase error. After compensating the phase error through the above methods, well focused high resolution range profiles (HRRPs) and high resolution images were obtained using range-Doppler (RD) algorithm. Theoretical analysis and simulated results verified the effectiveness of this method.