Abstract: In order to investigate the characteristics of photosynthesis changes of mango leaves under enhanced UV-B Radiation，the treatment of artificial simulation of enhanced UV-B radiation（24 and 96 kJ ·m-2 ·d-1） were conducted with the adult trees of‘Tainong 1’in the field，and the photochemical reactions， activities of key enzymes in carbon assimilation and the expression of gene were observed. The results showed that，compared to the control（natural lighting），there was a decrease of tree yield and soluble sugar and sugar-acid ratio of fruits under the 96 kJ ·m-2 ·d-1 treatment and no significant changes with 24 kJ · m-2 · d-1 tratment except that vitamin C was significantly higher than the control. Chlorophyll a/b value，net photosynthetic rate，stomatal conductance，transpiration rate and intercellular CO2concentration in leaves treated by 96 kJ · m-2 · d-1 were significantly lower than the control and treated by 24 kJ · m-2 · d-1，The content of photosynthetic pigment，the vitality of Hill reaction，the quenching coefficient of photochemistry the activities of Rubisco were significantly higher than the control. The Hill activity and Rubisco activity treated by 24 kJ · m-2 · d-1 were significantly higher than the control，net photosynthetic rate，stomatal conductance，transpiration rate，intercellular CO2 concentration and the content of photosynthetic pigment showed no significant difference compared to the control. The expression of coding gene of Rubisco big subunit（RbcL）could be inhibited by the 96 kJ · m-2 · d-1treatment 5th March and 22nd April. It is clear that stomatal limitation could be induced by 96 kJ · m-2 · d-1treatment directly，and then photosynthesis would be inhibited and then result in the reduction of yield and the deterioration of quality

Key words: mango, enhanced UV-B radiation, photosynthesis