Abstract: Taking Nitraria tangutorum,a perennial desert plant in the field environment,as material,scanning electron microscope was used to observe the microstructure of N.tangutorum leaf stomata underdifferent exogenous proline concentrations,and the length,width,area and density of the leaf epidermalstomatal apparatus were measured respectively,and the difference of the same index under different prolineconcentration treatments were compared.The concentrations of exogenous proline spraying were set at 50,100,150,200,250 mg·L^-1 respectively（Proline,abbreviated as Pro or P）under natural drought stress,and thedrought tolerance of N.tangutorum were tested respectively.The observation results showed that the stomataguard cells of N.tangutorum leaves were kidney-shaped,and the stomata were randomly distributed in the leafepidermis.The stomatal apparatus was mostly irregular,and the stomata were oval and leaf surface waxy less.And the leaf cells appeared folds and sinks.Compared with the control,under different concentration treatments and different sampling days,the stomata length,width and area decreased,and the stomata density increased.As the concentration increased and the number of sampling days changed,the overall stomata length showed adownward trend.When the concentration reached at 200 mg·L^-1,the decreasing amplitude increased,and theoverall width and area showed a trend of first decreased,then increased and then decreased,while the stomatadensity showed an overall upward trend.Among them,the stomata length,width and area were at aconcentration of 50 mg·L^-1,the number of sampling days reached the maximum on the first day,and thestomatal density reached the maximum at the concentration of 150 mg·L^-1 and the ninth day of the sampling days.In addition,the stomata length differed significantly on the first day,the sixth day,and the ninth day under thetreatment of different concentrations of proline,while the stomata width and area were not significantly different.Except for the beginning,the stomata density was different due to the different proline concentration.Thedifference was significant（P＜0.05）.The results showed that spraying different concentrations of exogenous prolineon N.tangutorum leaves under natural drought stress could reduce the length,width and area of the stomata,andincrease the density of stomata,could provide a theoretical basis for N.tangutorum drought resistance.