Research into blowouts has been carried out based on field survey and mapping combined with aerophotograph interpretation and analysis in HulunBuir sandy grassland,Inner Mongolia.It is discovered that:(1) a blowout consists of a pit hollowed out by aeolian erosion and an adjoining sand deposition transported by wind from the pit;(2) blowouts can be classified geomorphologically in accordance with their shape,stages of development,and initiating factors;(3) all of the three sandy tracts of HulunBuir sandy grassland are consisted of aeolian depressions and adjoining dunes formed by blowouts;(4) large scale occurrence of blowouts in Anthropocene is closely related with human activities,as result of environmental coupling event of the coinstantaneous extremity of drought and wide spread intense human disturbance of the fragile soil layer and sandy grassland ecosystem.The research is significant in the study of the initiation of sandy desertification,and in the study of geomorphology evolution of the sandy grassland.It will also be helpful to rational utilization of grasslands,and prevention and harness of sandy desertification of grasslands.