Abstract: Regarding the problem of the performance degradation of Capon adaptive beamformer due to steering vector error and the estimation error of covariance matrix, this paper proposes a new method that by way of averaging the noise eigenvalue which mainly effect on the robustness of the beamformer after the eigenvalue decomposition. An estimation of threshold value is obtained from the results of simulation experiments; and compared with traditional diagonal loading methods, this technique can achieve the same performance and be more effective and direct in practical application.