In order to solve brightness adaptation problems of driver go into tunnel’s interior from the outside, improve driving safety, a feasible scheme is given by this paper. It uses BH1750 to acquire realtime light intensity of tunnel’s outside, along with, used NRF24L01 to send and receive data, and uses PT4115 to drive LED. The system includes a host and four extension, the final test results show that this design can achieve better measurement of tunnel external light to control the LED light intensity, thus making the internal brightness with the brightness gradient outside the function, has certain practical and innovative.