Abstract: According to the field investigation in the natural grassland of the Xiliao River Plains,the tillers belonged to four or three age classes,and the rhizomes belonged to four age classes under different disturbance habitats. The numbers of the potential populations composed of winterness seedlings and buds were dominant in the first age class. Winterness seedlings belonged to three age classes, while buds belonged to four age classes under all disturbance habitats. The age structure of the potential populations showed an expanding age structure.