Abstract: In this study, the monthly dynamics of crude protein, crude ash, crude fiber and digestibility of four main herbage plants, Stipa breviflora, Stipa kirschner, Leymus chinensis and Artemisia frigida, in the desert steppe of Inner Mongolia were characterized. The differences in nutrient indices between different species in the same month and different months of the same species were statistically compared. The results showed that the in vitro digestibility of the four herbages was decreased with the extension of time. The crude ash content showed different changing rules among different species. While no obvious changes in crude protein content was observed in Artemisia frigida, the crude protein content of the other three plants was found to increase in initial stage and then decrease. The content of crude fibers was increased with the extension of time. The digestibility of forage was extremely significantly positively correlated with crude protein content, and the crude ash content was significantly positively correlated with crude protein content. Our results provide a scientific basis for improving the utilization efficiency of biological resources in desert steppe in this region.