Abstract: This manuscript summarizes a novel direction-of-arrival (DOA) method developed in recent years, which is called direction finding based on time modulated array (TMA) with harmonic characteristic analysis. Its advantages and disadvantages are compared with the existing direction finding methods. First, its origin, development and mathematic principle are analyzed. Second, the research status for direction finding based on TMA is summarized. Then, direction finding based on the two-element TMA, the multiple element TMA, and the TMA direction finding for broadband linear frequency modulation signals are discussed, and the mathematical principles, key techniques and implementations are analyzed in detail. Finally, the disadvantage and development tendency of direction finding based on TMAs are discussed and explored.