Abstract: Aiming to improve the low information utilization of direction-finding methods with the harmonic property analysis under time-modulated array (TMA), a multi-harmonic direction-finding method of TMA based on signal spectrum characteristic is proposed. By analyzing the signal frequency spectrum, the multi-harmonic direction-finding model is established and the best linear unbiased estimated formulation is derived, which can effectively improve the direction-finding accuracy and stability of TMA in the noise environment. The binary phase shift keying (BPSK) signal is provided as a typical communication signal to examine the effectiveness of the proposed method. Meanwhile, an S-band two element TMA is also constructed to verify its feasibility in the experiment.