Abstract: To explore the response of photosynthetic characteristics of Leymus chinensis to different grazing intensities under continuous grazing, the diurnal dynamics of photosynthetic characteristics in five grazing plots and one enclosing plot were measured using Li-6400 Portable Photosynthesis System. The correlations between the traits of parameters and grazing intensities (R) were analyzed. Daily variation of net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) appeared as a single peak curve and a double-peak curve in all plots on 16th August and 2nd September respectively, but intercellular CO₂ concentration (Ci) showed a U shape trend. In the enclosed plot, Pn, Tr, and Gs were higher than those in the grazed plots. In addition, Pn, Tr, and Gs decreased with an increase in grazing intensity, but Ci increased. It is suggested that the variation range is greater under higher grazing intensities. There were significant negative correlations between Pn, Tr, Gs and R but Ci was significantly positively correlated with R. There were significant differences in Pn, Tr, Gs and Ci among 6 grazing intensities on the two dates. Hence, herding intensity and hydrothermal conditions can inhibit photosynthesis by L. chinensis.