<p>This study addresses the vacuum sealing issue in the ultraviolet (UV) channel of a solar radiation simulator by optimizing the sealing structure to reduce energy attenuation in the UV spectrum. This improvement enhances the accuracy of photovoltaic module testing, solar product evaluation, and environmental simulation. A dovetail sealing groove structure is adopted, and the performance of an O-ring made of fluororubber is analyzed through simulations under different groove parameters. The results indicate that the chamfer of the groove opening, the bottom angle, and the compression ratio are key factors influencing sealing performance. A polynomial fitting method is employed to establish an approximate model, and the bat algorithm is used to optimize the groove parameters. Experimental results demonstrate that the optimized sealing structure exhibits excellent vacuum sealing performance, consistent with simulation predictions. This study provides a theoretical foundation for high-performance sealing design in solar radiation simulators and serves as a reference for other high-precision sealing applications.</p>