Using open-top Chambers(OTCs) and UV-lamps,we manipulated climate warming and enhanced UV-B radiation.The parameters of photosynthetic gas exchange and chlorophyll fluorescence of Picea asperata seedlings in the eastern fringe of the Tibetan Plateau,where climate warming and enhanced UV-B radiation(UV-B) were severe,were measured to investigate its photosynthetic responses to the two worsening environmental factors.The results showed that:(1)Enhanced UV-B restrained the net photosynthetic rate(Pⁿ),the maximum photosynthetic rate(P^max) and the apparent quantum yield(Φ).However,it increased the photosynthetic light compensation point(LCP).In addition,enhanced UV-B induced photo-inhibition of the photosynthetic system Ⅱ(PS Ⅱ) in P.asperata seedlings,and it reduced the effective quantum yield of PS Ⅱ(Φ^{PS Ⅱ}).In the end,enhanced UV-B significantly inhibited shoot elongation,root growth and biomass accumulation.(2)OTCs warming significantly enhanced Pⁿ and P^max,but it had no effects on G^s,T^r and Φ.(3)UV-B effects on photosynthesis were amended by warming to some extent,which could be judging from the increased Pⁿ,P^max,intrinsic efficiency(F^v/F^m) and Φ^PSⅡ of PSⅡ,and the improved growth.In the end,warming could alleviate the harmful effects of enhanced UV-B on photosynthesis of P.asperata.