Sinosenecio jishouensis D.G.Zhang,Y.Liu ＆ Q.E.as a new species belongings to Asteraceae,is considered to be a severely endanger species,whose natural populations were only discovered in Dehang canyon in Hunan Province,so far,our previous studies had indicated that low light intensity and high relative humidity are not the restricting factors to their distribution.Here,we further investigated impacts of drought stress on photosynthetic apparatus including the leaf relative water content(RWC),photosynthesis parameters and chlorophyll fluorescence parameters by using the plants of S.jishouensis which lives in shade.Results showed that:(1)RWC of S.jishouensis decreased continuously with the drought stress proceeding.When no watering sustained for 12 days,the RWC was less than 15% and plants could not survive.(2)Net photosynthetic rate(P_n),stomatal conductance(G_s) and transpiration rate(T_r) had decreased dramatically,while intercellular CO₂ concentration(C_i) had increased or no significantly change under drought.The results suggested the main reason for P_n decreasing was non-stomatal restriction.(3)When no watering sustained for 9~12 days,the value of the maximum efficiency of PSⅡ(F_v/F_m),effective quantum yield of PSⅡ photochemistry[Y(Ⅱ)] had decreased significantly and quantum yield of nonregulated energy dissipation in PSⅡ[Y(NO)] had increased obviously.These mean the PSⅡ were serious damaged and the non-photochemical quenching increased significantly.Conclusively,these results proved that S.jishouensis is sensitive to drought stress,which is probably the key cause for its distributing limit.