Abstract: Deceptive jamming technology against inverse synthetic aperture radar is mature at the present time, but the research on anti-jamming technology for ISAR (Inverse synthetic aperture radar)is deficient at home and abroad yet. Through the analysis on the theory of deceptive jamming technology against ISAR, a new method for anti-jamming against ISAR based on LFM (Linear frequency modulation) signal’s slope variation is presented in this paper. The false target’s echo energy is suppressed due to frequency modulation slope mismatching. Doppler domain averaging is adopted for improving the quality of the ISAR image, which helps automatic target recognition (ATR).Simulation result based on simulating data shows the validity of new algorithm.