To estimate direction of arrival for the coherent signals, a virtual array method for direction of arrival estimation based on unitary transformation is proposed. In this approach, the covariance matrix, which is obtained from virtual array, is reconstructed by utilizing a unitary transformation matrix. The simulation results verify that the proposed method has high performance of decorrelation and estimation. The proposed method can decorrelate the coherent sources without a lot of snapshots and a reduction in array aperture. All of matrix computation are in realvalued space, thus, the computation complexity is very low.