We look into the optimal structure for the DTV (Digital TV) receiver system with an array antenna. In this paper, we apply the ML(Maximum likelihood) approach, which is a classical method in the theory of detection and estimation. And we examine the limitation of it. It is that the number of multi-paths should be less than that of antennas. But it conflicts with the indoor channel environment. To deal with this problem, we propose a sub-optimal structure, which has lower complexity and computation load, as compared with the optimal structure. And to verify the performance, we compare the SER(symbol error rate) curve of each system by computer simulation.