The present invention is a high dynamic null widening method, comprising: obtaining the sampling data of the received signal of the array antenna, performing band-pass filtering, Hilbert transform and amplitude-phase correction, extracting the obtained sampling data at equal intervals, and then outputting them in two channels, one of which is Input FIFO module storage, and the other channel is extracted at equal intervals, and then sent to the QR decomposition unit for covariance matrix estimation, and the updated covariance matrix is output; forward iterative update of intermediate variables, according to the updated covariance matrix and intermediate variables Perform backward iterative calculations to obtain updated optimal weights; the sampled data of the estimated covariance matrix stored in the FIFO module is multiplied and added with the updated optimal weights, and then filtered and output. The invention equivalently expands the interference null, enhances the stability of filtering, and implements FPGA to enhance the stability of filtering.