This study presents a light transmission device with automatic adjusting brightness and heat flux. This device uses bimetallic strip as an important component of automatic brightness in the device, using bimetallic strip when heated bending angle changes the nature of the implementation according to the intensity of solar radiation and the outdoor temperature through or the function of keep out sunshine, to achieve the purpose of increase or decrease into the interior of the sun’s radiation, reducing the glare and energy consumption of air conditioning in summer. The adjustment performance of the light transmission device was analyzed by setting up the experimental room and the contrast room. The influence of the angle between the sun’s light and the bottom of the experiment room and the length to width ratio of the room was analyzed. It can be seen from the experimental analysis, the light transmission device at noon sun illumination the strongest shading rate of 2.56% ~ 6.47%.