The direction of arriving (DOA) estimation algorithms used in TD-SCDMA system to realize DOA detection would result in a large number of mathematical operations. Meanwhile, the number of DOA detection would be restricted by the number of array elements of a smart antenna. To solve this problem, a new method for DOA detection based on the orthogonal mid-amble sequence would be presented in this paper, which can be employed in system with beam-forming by the method of mplitude weighting of base-band signal (AWB). The directional transmitting of smart antenna can be achieved by this method without any method of conventional frequency spectrum search or DOA estimation algorithms. The parameters of DOA for mobile station could be detected by the new method, which could be used in a system with directional transmitting directly. The working principle of this new DOA estimation method would be introduced in this paper as well as its proving.