This article mainly develops white LED lighting with automatic light supplement. It is hoped that the circuit can judge the strength of the external light source to automatically control whether the lamp is on or not, so as to reduce the consumption of excess energy and save considerable energy over time. We use a photo resistor element to sense the change in the intensity of the external light source, and then use an operational amplifier as a comparator to compare the voltage rise and fall of the photo resistor due to light, so that the circuit can distinguish when to use the brighter mechanism, a more power-saving mechanism and when to use it. Finally, a white LED lighting system with automatic fill light was built to verify the theory and method of this article.