To effectively protect guided weapons and improve the combat effectiveness in the future high-tech war. Angle estimation of monopule in SF-LFM pulse compression radar will effected by the high power microwave weapon. First, this paper proposes the radar-receiver sum and difference channels moddel on which the HPM effects, then simulates radar system signal and information processing like digital pulse compression, monolulse angle estimation. Obtained data from Monte-Carlo experiments, this paper builds the qualitative and quantitative relations between accuracy of the angle measurement and strengh and correlation of the phase noise caused by HPM. These conclusions can provide reference for some HPMW design and application units.