Aimed at the problem that the utility of the traditional decorrelation algorithm to the array aperture is poor, this paper proposes an improved spatial smoothing algorithm. All the data information of the covariance matrix received signals are utilized fully by reconstructing subarray covariance matrix, and the spatialdifferencing matrix is built to suppress the effect of noise. Finally, the propagator method algorithm is adopted to estimate 2dimensional direction of arrival (DOA). The simulation shows that this algorithm is good in decorrelation algorithm, and high in computation precision compared with the traditional decorrelation algorithm.