Abstract: Frequency-stepped chirp signal is an effective radar signal which can utilize the digital signal processing to obtain high range resolution with relatively narrow instantaneous bandwidth. Because the anti-jamming ability of frequency-stepped chirp signal radar is not enough, the random frequency-stepped chirp signal is designed, and a random frequency-stepped chirp signal ISAR imaging algorithm based on compress sensing theory is proposed. The range profile and high resolution 2-D ISAR image can be obtained with fewer subpulses. Then, the target velocitys influence on frequency-stepped chirp signal radar imaging is analyzed, the random frequency-stepped chirp signal which contains velocity measuring subpulses is designed, and the velocity estimate and compensation method which is combined with time-frequency analysis, Radon transform and binary mathematical morphology is proposed. The simulation verifies the capability of random frequency-stepped chirp signal ISAR and effectiveness of the imaging algorithm proposed in this paper.