Abstract: Investigation on grassland sorts and grassland plant resource was carried out in Sunan Yuguor and Subei Mongolian Autonomous County, Gansu province in 2007-2008. 226 grass quadrates, 125 shrub quadrates, and 32 mixture quadrates were tested; 22 500 km² of investigation area were labeled on the topographic map. The investigation route was 185 000 km. According to the “Chinese Grassland Divisional Criteria and Chinese Grassland Classification System”, It was sure that the grassland in Sunan county embraced 29 types of 24 forms belonged to 18 subclasses in 9 classes, respectively; and the grassland in Subei county were 29 types of 19 forms from 17 subclasses in 9 classes. 986 plant samples of 381 species from 176 genera of 53 families were collected. Among the plants, 300 species were forage grass. The general situation of grassland in Sunan and Subei counties was degradation. Partial area is preserved well; beside climate factor, overgrazing is the key cause that induced the grassland degradation; the next reason is the rodent damage. Grasshopper is not the cause bringing grassland degradation. The species diversity of grassland plant in the investigation area has not been destroyed greatly. However, the species dominance in the plant community had a large variation, which shows that the change of species relation in the community has already taken place. The biodiversity is suffering threat.