A method for regulating a sound source of a designated object and an audio processing device using same are provided. The method includes the following steps. An original two-channel signal is obtained. An included angle of the designated object with respect to an ear of a user is detected. A first beam and a second beam are respectively formed in a clockwise direction and a counterclockwise direction according to the included angle to obtain a bidirectional sound signal. A sound rotation process is performed, so that the ear is directed toward sound source of the designated object, and a rotated two-channel sound signal is obtained. A unidirectional sound signal towards the sound source is obtained. A sound signal characteristic of the designated object is obtained according to the bidirectional sound signal and the unidirectional sound signal and then is regulated to synthesize a regulated two-channel signal.