The phase signature of active decoy and its application in angular deception Jamming using Interrupted-Sampling Repeater Jamming(ISRJ) were investigated in detail. After the principles of ISRJ were expounded, the phase signature of different-order active decoy and the influential factors were analyzed. According to the principle of monopulse radar angle tracking, several conditions that should be met for jamming source were deduced, including the repeater power, the delay time and frequency of repeater. Then, the effects of correlative and non-correlative interference on angular deception were discussed, respectively. Simulation results show that the decoy can bait monopulse radar system by flexible parameter design. This research is beneficial to the jamming design and use of ISRJ．