Abstract: The design of direction of arrival (DOA) estimation algorithm is the key technology of smart antennas system. It is very important to design an algorithm of DOA estimation with clear physical model and lower complexity of mathematics process. In this article, a novel spectrum search algorithm, MIDOA spectrum search algorithm, is presented, which is based the feasible use of midamble sequence defined in TD-SCDMA standard (TD), and is one simple practical baseband DOA estimate method. Firstly, we propose the physical model of midamble sequence receiver of TD-SCDMA smart antennas with 8 array element circle formation. Based on the physical model, the mathematics formulations for the receiving process are also presented. Then according to the physical model and the mathematics formulations, we give MIDOA spectrum search algorithm as well as the corresponding flow chart. The simulation results and performance analysis show this method is one simple feasible estimate method of DOA in view of the TD standard. Compared with MUSIC algorithm, the MIDOA spectrum search algorithm is characterized with clear physical model and high robustness. And the number of DOA that can be estimated will not be restricted by the array element number of smart antennas array.