Channel blind equalization algorithm based on Eigen-Decomposition (ED) of data covariance matrix can be applied to calibrate the channel mismatch for multi-channel SAR/GMTI system. However, this algorithm has a disadvantage that it suffers from a slow convergence rate. In this paper, the principle of channel blind equalization algorithm is firstly investigated. Then, to improve its convergence rate, reduced-dimension technique is used into this algorithm and a new channel blind equalization algorithm is proposed. Experimental results on simulation data and measured SAR data demonstrate that compared with the conventional channel blind equalization algorithm, the proposed algorithm shows a fast convergence rate and is able to calibrate channel mismatch with much less sample support.