Abstract: In order to explore salt tolerance ability of Bmicrophylla, took half a year old seedlings of endemic species in Xinjiang region as the experimental materials, and measured the chlorophyll fluorescence parameters index under different simulated NaCl concentrations. The results showed that a negative relation was founded, which maximal photochemical efficiency of PSⅡ in dark (Fv/Fm), photochemical quenching coefficient (qP) and intrinsic PSⅡ efficiency (ETR) decreased gradually with rising of NaCl concentration; nonphotochemical quenching parameter increased under the same conditions, and there were highly significant differences along with the prolonging of stress time. The results indicated that Betula microphylla var．paludosa has stronger salinity tolerant.