Outdoor Acceletated Weathering Equipment is the most widely used outdoor acceletated weathering test method in the world today. The success in development of this equipment will have a far-reaching and promoted effect on R&D of new material and new dope. Automatic and all-weather tracing solar is the tackle key problem. A new method of tracking the sun is presented, and the sun track is corrected with this method. The operation principle of a solar-tracking sensor is introduced.