Based on the actual climatic data from 1981 to 2000 in Northeast China, the predicted climatic data and the actual distribution data of Stipa species, 12 climatic factor indicators affecting Stipa species distribution were extracted combining with similar biological and ecological characteristics of Stipa. By introducing Gauss Competitive Exclusion Principle and the statistical analysis method, a competitive stochastic mathematical model of the distribution of Stipa was built, and the corresponding algorithm was given. The forecast figures were obtained for the optimal, medium and general adaptable distribution of the five Stipa species from 2041 to 2050 and from 2091 to 2100. Furthermore, by analyzing the prediction, it was shown that the climate change and inter-specific competition were the main impact factors for predicting the distribution of Stipa baicalensis Roshev, Stipa klemenzii Roshev and Stipa breviflora Griseb, and the inter-specific competition is the most impact factor for predicting the distribution of Stipa grandis P.Smirn and Stipa krylovii Roshev from the medium-term results. From the perspective of long-term results, the climate change is the important reason for affecting five Stipa species competitive distribution.