Abstract: For imaging processing of synthetic aperture radar, speckles usually are removed with multi-look processing. According to the features of multi-look processing of SAR, a new, high efficient realization method is presented in this paper. It utilizes the poly-phase structure of filter bank to change the order of down-sample processing and filtering, thus diminishing the data quantity to be processed, and at the same time reduces the computation volume. All these are advantageous to real time processing.