This invention is one kind satisfies a need the headlight automatic control installment, the department mainly by a microprocessor, a state of roads sensing unit, a motor driver, a connection interface is composed; And this microprocessor is examines by the state of roads sensing unit knows the road surface the condition like curve, uphill, state of roads and so on downhill, then by the motor driver control headlight illumination angle, and penetrates the connection interface control auxiliary headlight to lighten; , as soon as so, this invention then provides satisfies a need the headlight automatic control installment, does not need the driver to cut voluntarily opens shuts the headlight, and may shift to an earlier time illuminates to the night driving line of sight dead angle, promotes the traffic safety effectively.