Aeolian desertification is one of the most severe eco-environmental issues in the area around the Qinghai Lake. By using meteorological data during 1958-2007 collected from Gangcha Meteorological Station on the shore of Qinghai Lake and social-economic data of Gangcha County during 1976-2007, we analyzed the driving forces of aeolian desertification there in recent 30 years through Principal Component Analysis. Results showed that from 1976 to 2007, both natural and human factors contributed to the variation of aeolian desertification area, while contribution rates of annual average wind speed change and arable land change were the primate driving factors of aeolian desertification varied at different stages during 1976-2007: (1) The expansion of aeolian desertification area in 1976-1987 was induced by human activities when temperature and precipitation increased; (2) increase of aeolian desertification area by 17.28 km2 from 1987 to 1995 was caused by the interaction of natural and human factors, in which natural factors played a dominant role while human factors intensified the role; and (3) during 1995-2007, human factors hastened the increase of aeolian desertification area when climate was warm-humid and wind speed decreased. In conclusion, the expansion of aeolian desertification area in Gangcha County was the result of mutual interaction among the dry-wet fluctuation, the human activities and aeolian desertified land in the frail alpine ecosystem.