Abstract: Due to the restrictions of the airborne radar's volume and weight, the traditional methods are not able to obtain the optimal clutter suppression results under the situation of low complexity. Based on the analysis of the structure of multistage Wiener filter, a multistage Wiener filter with variable diagonal loading is proposed. The backward-recursive algorithm of this method is developed to suppress airborne radar's clutter. Simulation results validate the feasibility and effectiveness of the new method and demonstrate that the proposed method is more robust and outperforms the traditional methods in low dimensional filter structure. Also in airborne radar's clutter suppression, the method can achieve the null-depth of -80dB.