Using digital beam-forming (DBF) can relieve the contradiction between high resolution in azimuth and wide measuring range of conventional synthetic aperture radar (SAR) system by increasing the measurement swath, while deviations between range channels will deviate the synthetic beam pattern from the expected form and impair the performance of the system. To address the issue, a method of DBF combined with channel equalization algorithm is presented. Firstly, the traditional DBF method is introduced briefly; then, the form of deviations between range channels is analyzed; finally, channel equalization algorithm is combined into traditional DBF method according to the analysis. The method can compensate deviations between channels validly and improve the result of DBF processing. Airborne flight experiments with eight range channels validate the proposed method.