A experiment on leaf litter decomposition was carried out to evaluate the effects of UV-B radiation on the chemical composition and subsequent decomposition of leaf litter in humid subtropical forest systems. The leaf litter was derived from Cyclobalanopsis glauca seedlings exposed to elevated and ambient ultraviolet B (UV-B) radiation treatments during growth for one year. The results showed that UV-B treatment significantly increased the original N, K and P content of leaf litter by 154.9%, 29.8% and 9.7%, respectively, and decreased the ratios of C: N, lignin: N and C: P of leaf litter by 60.5%, 61.7% and 8.5%, respectively (P < 0.05), but had no significant effect on C and lignin content. The decomposition of leaf litter derived from seedlings exposed to elevated UV-B treatment during growth was faster, but did not show significant difference from that of ambient UV-B treatment. Exposure to elevated UV-B radiation during growth did not significantly influence the K release, but promoted the P release and retarded the N accumulation during leaf litter decomposition. Our result will contribute to the better understanding of the role of UV-B radiation in moist subtropical forest ecosystem.