【Objective】The objective of this paper was to explore the effects of overseeding on species richness and aboveground biomass in Maqu alpine desertified meadow in Gansu Province. 【Method】The experiment of overseeding was carried out in Maqu alpine desertified meadow from 2006-2007. 【Result】The overseeding increased species richness in 2006， but decreased it in 2007. The aboveground biomass of grass occupied the major parts and significantly increased after overseeding treatments. In 2007 growing season， the aboveground biomass of all treatments was significantly higher than that in 2006. The aboveground biomass of Elymus nutans， Festuca sinensis and Poa pratensis L. increased most significantly after overseeding treatments. 【Conclusion】The overseeding treatment of Elymus nutans， Festuca sinensis and Poa pratensis L. was one of the best overseeding combinations for application in Maqu alpine desertified meadows.