Abstract: The Bayanbulak ecological station has records of the representative plant vegetative stages between 1984-1990 and 2004-2008 periods. Based on the climate index and net primary productivity (NPP) of the station this paper analyzes the NPP by the Beijing Model, the integrated vegetation model, and the Linghuilong building model. The modeling and measured values were fitted by linear regression and the carrying capacity of Bayanbulak grassland was estimated. 1) the modeling values calculated from the Beijing model(R=0.857^**), integrated vegetation model (R=0.894^**), and Linghuilong building model(R=0.894^**) all fit well with the observational values; 2) precipitation rather than temperature is the determinant factor influencing the NPP of Bayanbulak grassland; 3) as the annual temperature increases 2 and 4℃ and precipitation increases 20%, the carrying capacity will increase from 0.94 sheep units per hectare (Beijing model) to 1.94 sheep units per hectare (integrated vegetation model) and 1.62 sheep units per hectare (Linghuilong building model).