The study site is located in Siziwang Banner of Inner Mongolia. Taking the Stipa breviflora desert steppe grassland as the research object, based on the individual scale of the plant, we analyzed the relationship between plant species diversity, plant diversity and productivity by field experiment of wild plants in 2016, The responses of the gradient ［0 (CK), 0.91 (LG), 1.82 (MG), 2.71 (HG) sheep / (hm²·a^-1)］ were studied. The results showed that: (1) there were 30 species of 13 families and 13 species in the control area, only one species of Allium ramosum in the light grazing area. Compared with the control area, the vegetation species in moderate and heavy grazing areas were reduced by 30% and 40%, respectively, among them, most of the reduced species belonged to perennial miscellaneous grasses and perennial rhizome grasses.(2) The functional group structure had different responses to the stocking rate, and the perennial clover had always dominated the desert steppe and increased with the increase of the stocking rate. The results showed that the other four functional groups showed a decreasing trend with the increase of the stocking rate. (3) In the two diversity indices, the other diversity indices were in addition to the Margalef index of the functional group diversity and the size of the control > light> moderate> heavy grazing area. (4) The results showed that there was a significant positive correlation between the three α diversity index and the grassland productivity (P<0.05), and the functional diversity index had no correlation with the productivity (P> 0.05). In summary, the study shows that longterm grazing makes the desert grassland community structure tends to be simplified, so that perennial grassland formation advantages of a single species. In addition, the increase in stocking rate makes the diversity and productivity of S. breviflora desert steppe grassland plants significantly decrease, and high levels of diversity lead to high levels of grassland productivity. Comparing the two diversity index indicators, the species diversity index contributes more to the productivity of the desert grassland.