Qilian mountain is the most important ecological security barrier in west China. Qilian mountain cultivate A piece of oasis like a standing-still “wet island” with desert on its north and west，the Loess Plateau on its east，and the Qaidam Basin on its south cutting off the southward invasion of the Badanjilin Desert and the Tengger Desert，thus protecting the ecological security of The Qinghai-Tibet Plateau “and source of three rivers known as Chinese Water Tower”，its ecological status is extremely important. Higher requirements of the balance between economic development and ecological protection in the Qilian Mountain National Nature Reserve have been put forward in recent years along with the increase of the indigenous population in the Qilian Mountain National Nature Reserve and people's need for rapid social and economic development. This paper would discuss the history of the destruction in the Qilian Mountain National Nature Reserve based on the Social environmentology by means of sociological research methods such as field investigation，questionnaire survey and semi-structured interview；and make classified statistic summary from five aspects such as the forest destruction，over-exploitation of mineral resources，destruction of hydropower station，overgrazing and damage from tourism. Illustrate from different aspects the root cause of heavy damage in the Qilian Mountain National Nature Reserve according to current situation，get the final conclusion for the cause of serious damage in the Qilian Mountain National Nature Reserve — lacks a strong accountability and response mechanisms towards the destruction of ecological environment at the legislative level；the role of policy instrument is not given a full play in the process of policy implementation namely policy implementation is not a complete one；evaluation of ecological environment protection policy of Qilian Mountain region is less；Ignore the related interest groups demand；lack of environmental protection consciousness education；the lack of unified，standardized and highly efficient management.