A false target jamming method based on step-wave frequency modulation is introduced. The principle of frequency-shift based on different segmentations onto Linear Frequency Modulation(LFM) signal is analyzed and the matched filter result of the jamming signal is also discussed. According to the time-frequency coupling property of LFM signal, multiple false targets can be created after matched filter. The correctness and effectiveness of the proposed method is verified through simulations. The results of uniform modulation and non-uniform modulation are presented. The proposed method is valid and produces false targets with various amplitudes and intervals.