Abstract:The damages of Hypnum fertile (Bryopsida: Musci) and its physiological responses were studied under enhanced UV-B radiation for 3 weeks. The doses of biologically effective UV-B irradiation were 6.93 kJ m-2d-1 (ambient UV-B radiation) and 9.01 kJ m-2d-1 (enhanced UV-B radiation, about 30% higher than ambient UV-B radiation), respectively. The results showed that the contents of chlorophyll and carotenoid of H. fertile both decreased with time under enhanced UV-B radiation, whereas MDA content significantly increased，and the activities of SOD, POD and CAT all increased. It is suggested that enhanced UV-B radiation caused oxidative stress to H. fertile and the oxidative stress might be alleviated by increasing the enzymes activities.