Abstract: To solve the problem of target detection in complex environment, radar system needs more gain and degree of freedom to control the sidelobe level and employ effective anti-jamming technology simultaneously. A modified anti-jamming method based on phased-MIMO radar is proposed, which combines the advantages of high gain and degree of freedom, to improve the anti-jamming performance. Different subarray with orthogonal signal are used in transmitting array, while forming nulls in each subarray. Matched filtering is used to achieve the waveform diversity. Furthermore, the raise of sidelobe level caused by nulls is vanished by reconstructing the data covariance matrix while controlling the sidelobe level by window function. This proposed algorithm can maintain a low sidelobe level and form series nulls even in complex environment. Simulation results prove the efficiency of this algorithm.