One year seedlings of Calligonum arborescens from Minqin in Gansu province were treated with different concentrations of NaCl (0,50,100,200,300 mmol·L^-1). We analyzed the photosynthetic characteristics and made the gray correlation analysis between physiological indexes and aboveground biomass, to explore the salt tolerance mechanism of desert plants, provide a theoretical basis for C. arborescens to better adapt to the virtual environment and to protect and restore the stability and sustainability of desert ecosystems. The results showed that, with the increasing of NaCl concentration, proline content gradually increased, in opposition to the change in soluble sugar. the photosynthetic parameters increased obviously under 50 mmol·L^-1 NaCl, and the net photosynthetic rate, stomatal conductance and transpiration rate reached the maximum, and significantly increased by 33.3%,68.0% and 60.8% compared with the control, the net photosynthetic rate, stomatal conductance and transpiration rate decreased when the concentration was more than 50 mmol·L^-1 compared with 50 mmol·L^-1 NaCl. The content of chlorophyll b decreased with the increasing of NaCl concentration while chlorophyll a and chlorophyll increased first and then decreased. Gray correlation analysis showed that transpiration rate, stomatal conductance, intercellular CO₂ concentration and chlorophyll b were significantly correlated with aboveground biomass. The research showed, low NaCl concentrations improving the growth of plants by activating certain mechanisms of plants. Through the adjustment of proline and soluble sugar contents, reducing chlorophyll content, net photosynthetic rate and transpiration rate, plants could maintain growth under high salt concentration.