In order to solve the problem that the adaptive monopulse phase discriminating curve is distorted and the performance of angle estimation is seriously degraded under the condition of main-lobe interference, a new method to improve the performance of angle measurement is proposed by introducing mirror virtual interference to offset the error generated by the interference signal.The distortion of phase discriminating curve and residual interference signal are analyzed mathematically to be the main factors of generating angle measurement errors,and the main angle of interference signal has a corresponding relationship with the deviation.Therefore,the sampling covariance matrix is reconstructed by mirror virtual interference to estimate the signal adaptively.The proposed algorithm does not require additional restrictions on the sum and difference beams,does not consume the degree-of-freedom of the antenna,and has higher stability under low SNR conditions.The simulation results demonstrate the effectiveness of the proposed method.