The time delay of output signal is sensitive to the frequency of input signal in LFM pulse compression radars. In light of this, a novel repeat jamming is presented based on pulse separation in which the separated pulses are retransmitted in a rearranged order. After the matched filtering, a set of false targets were induced. The jamming technique was explained in detail with group delay theory. Formulas of separation number on condition that false targets hold amplitude dominance and retransmitted order with the maximum number of false targets were presented. Finally, the theoretical analysis was verified by the simulation results.