This invention is one kind may supply automatically changes the illumination auxiliary the headlight, is equipped with a control circuit in the headlight, this control circuit is contains has a microprocessor, one side to examine to the angle knows the unit and an actuation headlight internal rotation installs motor's driving circuit; This lateral angle examines knows can 夠 the response march forward vehicles' lateral angle to give the microprocessor, after microprocessor computation actual corner, outputs one pair to compensate this corner the motor control signal to the driving circuit, this driving circuit adjustment head lamp main body reflects the chimney to deflect a vehicles corner the angle, so, the headlight namely has examines automatically knows the corner, but adjusts the illumination angle, thus provides may illuminate the turning state of roads optical fiber, enhances the tortuous path to go at night the time security.