The CO2 cycloaddition of epoxides is a highly attractive long-term carbon fixation strategy, but harsh reaction conditions and expensive catalytic materials limit its industrial application. Herein, low-cost and highly efficient W18O49-based composites were constructed by in-situ solvothermal synthesis. It is found that W18O49/g-C3N4 composites exhibit the highest yield of 74% (271 mmol g−1h−1) in the probing reaction of styrene carbonate production. The physicochemical characterizations indicate that the photocatalysis plays a fundamental role in this reaction by promoting the activation of CO2 and styrene oxide. The crucial role of photogenerated electrons and Lewis acid-base sites is confirmed. In this work, a novel catalyst selection to produce cyclic carbonate under ambient conditions is presented. © 2023 Elsevier B.V.