A communication device for estimating the azimuth angle includes a receiving module and an estimating module. The receiving module is configured to sequentially switch several azimuth angles to receive a first signal transmitted at the first transmitting angle from a first transmitting module of the first communication device. The estimation module is configured to calculate several signal powers of the first signal received by the receiving module at the several azimuth angles; to determine the maximum signal power among the several signal powers; to determine the pre-judged AOD according to the azimuth angle of the maximum signal; and to calculate the AOD of the associated first signal based on the pre-judged AOD and at least one azimuth angle adjacent to the pre-judged AOD among the several azimuth angles.