Abstract: This article provides an overview of the research progress of upconversion composite materials in photocatalysis. Due to the low utilization rate of solar radiation by traditional photocatalytic semiconductor materials, their practical application in environmental governance and energy conversion is limited. Upconversion composite materials can convert low-energy radiation into high-energy emission, improve the responsiveness of photocatalysts to infrared-visible light, and thus improve the utilization rate of solar energy. This article first elaborates on the basic principles and application prospects of photocatalytic reactions and then focuses on the preparation methods, performance characteristics, advantages, and disadvantages of three types of upconversion composite photocatalysts: Rare earth, quantum dots, and triplet-triplet annihilation. It also introduces optimization strategies that use precious metals or alloys to enhance upconversion effects and charge separation efficiency with examples. The purpose of this article is to provide new ideas and references for photocatalysis research and promote the application and development of upconversion composite materials in the field of photocatalysis.