The present invention provides a device of controlling a treadmill via voice. The device comprises a sound reception unit used for receiving the sound of the users via a microphone; a character identification unit used for converting the sound received by the sound reception unit into the characters; an instruction conversion unit used for converting the characters identified by the character identification unit into the instructions; an instruction execution unit used for a device corresponding to the treadmill to receive and execute the instructions converted by the instruction conversion unit. According to the present invention, the treadmill can realize the different functions via the voice of the users, and users can use the different functions of the treadmill conveniently when running.