In order to research the effects of different stocking rates on the age-structure and ecological niche of Stipa breviflora population， the study was conducted on the Stipa breviflora steppe desert in Siziwang Banner， Ulanqab City， Inner Mongolia， China. A single factor random complete block design was adopted， and a comparative analysis was conducted using static life tables， ecology niche width， and ecology niche overlap index. The results showed that the age-structure of the population of Stipa breviflora changed with changing in stocking rate. With an increase in stocking rate （below the level of moderate grazing stocking rate）， individuals in the Stipa breviflora population increased from C03 level （diameter of bunch 1.1-2.1 cm） to C08 level （diameter of bunch 6.1-7.1 cm）， thereby ensuring that individuals achieve their expected physiological lifespan； Heavy grazing led to “fragmentation” and “juvenilization” of individuals of Stipa breviflora， and the mortality rate of Stipa breviflora was evenly distributed among all age groups. Below the level of moderate grazing stocking rate， the ecological niche width of the middle and elderly age groups of Stipa breviflora was relatively small， and the competition intensity among individuals was relatively weakness； The ecological niche overlap among young and middle-aged individuals was relatively high， and there was intense competition among individuals； However， heavy grazing not only led to “aggregation” and “juvenile” of Stipa breviflora individuals， but also increased the intensity of competition among individuals， resulting in intensified competition between young and middle-aged individuals. In summary， Stipa breviflora resisted grazing disturbance by transitioning from high individual age groups （young and middle-aged） to middle and elderly groups below moderate grazing stocking rate， but heavy grazing resisted grazing disturbance by “aggregation” and “juvenile” of middle and elderly individuals， thereby ensuring that the population is in an absolute dominant position in the community.

Stocking rate  /  Stipa breviflora  /  Age-structure  /  Ecology niche