A variable-frequency speed-adjustable three-phase asynchronous motor, comprising a motor base (1), a fixing ring (3) provided on the inner side at the rear extremity of the motor base (1) for fixing a stator iron core (2), a temperature sensor (4) provided on the fixing ring (3), a front extremity cover (5) and a rear extremity cover (6) provided at either the front or rear side of the motor base (1), a rotor fixed within the motor base (1), bearings provided on either extremity of the rotor, bearing supports provided on the front extremity cover (5) and on the rear extremity cover (6), vents provided on the front extremity cover (5) and on the rear extremity cover (6), a fan and a windshield (7) provided at the rear side of the rear extremity cover (6), a junction box (8) provided on the motor base (1), an alarm device (9) provided on the junction box (8), a fixing groove (11) provided at the upper extremity of the junction box (8), an insulating plastic fixing layer (12) provided within the fixing groove (11), and a display screen (10) fixed on the insulating plastic fixing layer (12), the temperature sensor (4), the alarm device (9), and the display screen (10) being connected to a control device in the junction box (8), and the control device being connected to a timing module. The variable-frequency speed-adjustable three-phase asynchronous motor is structurally simple and reasonably designed, facilitates a user to learn in a timely manner the internal temperature of the motor and the time over which the motor is in use, and alerts the user when overheating.