Aimed at the different response of the main and auxiliary antennas to the Crosspolarized interference in SLB，a new question that releasing mainlobe Crosspolarized interference to the radar system with SLB may arouse SLB system works and the target must be hidden is proposed. The model is set up and the effect of the interference is analyzed. The simulation results show that whether deceptive jamming or blanket jamming to the main antenna, mainlobe Crosspolarized interference can change the responses of signals from main and auxiliary antennas. The energy received by the main antenna decreases rapidly, and the energy received by the auxiliary antenna is stronger than that of the main antenna, thus triggering off SLB system to work. And simultaneously the main antenna channel closes and the target vanishes.