Abstract: Cordyceps sinensis was an expensive medicinal fungus in the Tibet Plateau. The excavation of the C. sinensis seriously affected the ecological environment. The excavation plots and control plots were set in Zeku County, Maqin County and Zaduo County, where were high production areas of C. sinensis in the Sanjiangyuan region. Field sampling investigation and statistical analysis were applied to assess the impact of C. sinensis excavation on the grassland vegetation. The results showed that, since excavation of C. sinensis, species diversity expressed as Shannon-Wiener indexes decreased by 10.3%-12.5%, community dominance expressed as Berger-Parker indexes increased by 16.7%-31.8%, vegetation coverage decreased by 10.6%-19.1%, and aboveground biomass decreased by 20.7%-46.1%. However, underground biomass not significantly changed under excavation of C. sinensis. Grassland degradation would impede the formation of C. sinensis. Therefore, it was necessary to protect the vegetation in the production areas for the sustainable utilization of C, sinensis resource. Aboveground biomass was the most sensitive variable to C. sinensis excavation, which could be used as the evaluation indicator in vegetation protection. The impact of excavation on aboveground biomass significantly related with the geographical locations, which means a necessity to make the protection strategy distinctively. Thus, further studies considering the climatic characteristics and soil properties were needed.