Abstract: The performance of space-time adaptive processing (STAP) decreases severelcy since the clutter covariance matrix can not be estimated accurately in forward-looking airborne radar (FLAR), due to the clutter range dependence. The registration-based method (RBC) can compensate the clutter range dependence well. However, when the moving target exists in the ground clutter, its information disperses in the space-time plain after applying the RBC method to the ground clutter. In view of these problems, we propose a moving target information constraint compensation method. The proposed method adds the moving target information protection constraint in the RBC method due to that the Doppler frequency of the clutter is different from that of the moving target. The computer simulation results show that the proposed method can compensate the clutter range dependence, and protect the moving target as well.