Speed changing box lock of braking device with motor

The utility model discloses a speed changing box lock for theft prevention of an automobile. The speed changing box lock comprises a lock shell, a locking mechanism arranged in the lock shell, a motor connected with the locking mechanism, and a motor stroke control device connected with the motor, wherein a motor braking circuit is connected between the motor and the motor stroke control device; the motor braking circuit comprises normally open switches which are connected at two ends of the motor, and a driving circuit which is controlled by a stroke switch contact on the motor stroke control device and can control the normally open switches. As the motor braking circuit is adopted, when the speed changing box of the automobile works, the motor with very high rotation speed can be braked in time after the power is cut off and the inertia rotation of the motor is reduced, thus preventing the overlarge inertia rotation of the motor and follow-up mechanisms from being overshot and clamped due to incapability of