Abstract: High-resolution spatial spectrum estimation algorithm required that multi-channel signals were sampled synchronously. If multi-channel signals were sampled asynchronously, non-synchronous sampling error would introduce deviation of spatial spectrum estimation. In order to compensate the non-synchronous sampling error, this paper proposed a new compensation method——forward and back symmetrical sampling method. This method used the reconstructed array signals which were added data of forward and back sampled data to compute the spatial spectrum. When the alternate sampling delay was accurate, because of symmetry, the added array error matrix was a real matrix which had no influence on the phase of the direction vector. In consequence, unbiased estimation of spatial spectrum can be realized. Theoretical analyses and simulation results showed that this method can eliminate the influence of non-synchronous sampling error when the alternate sampling delay was accurate, and its performance was similar to the remodeling method; When the alternate sampling delay was not accurate, its performance was better than the remodeling method. The new method has the advantages of lower complexity and it is not necessary to know sampling delay time. Therefore, the forward and back symmetrical sampling method is an effective compensation method for non-synchronous sampling error of spatial spectrum estimation.