This work proposes a new method to estimate direction-of-arrival (DOA) for directional antenna arrays. An obvious modification in the proposed method is the inclusion of changes of array gain in matrix calculation. This method is proposed in order to suit the characteristic of directional antenna array. Computer simulations are performed to verify the performance of the proposed method. Simulations results show that the proposed method significantly improves the estimation resolution up to 10°. The proposed method also improves error of estimation provided that number of snapshots is more than 150, SNR is more than 5dB and signals separation is not more than 13°. In general, the proposed method has outperformed conventional method in DOA estimation for directional antenna array.