The airborne conformal array (CFA) radar's clutter rid-ges are range-modulated, which result in a bias in the estima-tion of the clutter covariance matrix (CCM) of the cell under test (CUT), further, reducing the clutter suppression performance of the airborne CFA radar. The clutter ridges can be effectively compensated by the space-time separation interpolation (STS-INT) method, which costs less computation than the space-time interpolation (STINT) method, but the performance of interpola-tion algorithms is seriously affected by the short-range clutter, especially near the platform height. Location distributions of CFA are free, which yields serious impact that range spaces of steer-ing vector matrices are non-orthogonal complement and even no longer disjoint. Further, a new method is proposed that the short-range clutter is pre-processed by oblique projection with the in-tersected range spaces (OPIRS), and then clutter data after be-ing pre-processed are compensated to the desired range bin through the STSINT method. The OPIRS also has good compa-tibility and can be used in combination with many existing me-thods. At the same time, oblique projectors of OPIRS can be ob-tained in advance, so the proposed method has almost the same computational load as the traditional compensation method. In addition, the proposed method can perform well when the chan-nel error exists. Computer simulation results verify the effective-ness of the proposed method.