A motor vehicle headlight positioning device consisting of a holder base, a headlight support, a step motor, a movable member and a swivel arm is disclosed. The headlight support is pivotally mounted in the holder base to hold a motor vehicle headlight. By means of the rotation of an output screw of the step motor to move the movable member linearly, the headlight support is rotatable by the movable member and the swivel arm to adjust the projecting direction of the motor vehicle headlight. As the output screw is rotated on its own axis and the output screw is supported in a support block of the holder base, the displacement stability of the movable member is enhanced.