Oak-pine mixed forests is one of the most typical types of forest in Qinling Mountains, and it's stability plays an important role in the biodiversity maintenance, carbon and water balance, and climate regulation in the Qinling Mountains. Common constructive tree species of oak-pine mixed forests in Qinling region include Pinus tabuliformis, P. armandi, Quercus aliena var. acuteserrata, and Quercus acutissima. Community stability of the pine-oak mixed forests is of great importance to their eco-functions regarding biodiversity maintenance, water-carbon balance, climatic regulation, and water-soil conservation in the vast area of Qinling Mountains. However, quantitative evaluation for the community stability of pine-oak mixed forests is presently lacking. The aims of the present study included: (1) to evaluate community stability of oak-pine mixed forest; (2) to explore the relationship between community stability and biodiversity of pine-oak mixed forest; and (3) to clarify spatial distribution pattern of oak-pine mixed forest community stability. Twenty-eight forest plots were selected from a typical oak-pine mixed forest community in the Huoditang Forest Area in Qinling region and surveyed based on the theory of multi-indicator multi-factor comprehensive evaluation. 28 community indicators were investigated in 28 plots, and were analyzed by PCA to get stability index values (F) in Huoditang forest region of Qinling Mountains. F values were clustered by Ward clustering method, and the cluster groups were cut by Mantel- optimal number of clusters (Ward clustering). Stability classes were classified according to the cluster groups. The results showed that: the stabilities were divided into three grades: high stable plots: F value was from 0.66 to1.13, average stand age was 58, accounted for total plot of 39.3%, medium stable plots: F value was from -0.28 to 0.34, average stand age was 46, accounted for total plots of 42.8%, low stable plots: F value was from -2.34 to -1.26, average stand age was 42, accounted for total plots of 17.9%. Among first 3 main components, diversity indexes of shrub and herb layer, elevation, soil moisture physical properties, stand density and DBH of dominant tree species undertook large load, and were key factors that influenced community stability. F value was significantly negatively linear fitted Shannon-Wiener index of the tree layer, and positively linear fitted with of Simpson index of shrub layer and species richness of herbaceous layer (P < 0.01). Multivariate curve fitting reached significant levels between F values and elevation and slope (R²=0.786, P < 0.0001). Greater stability of pine-oak mixed forests was in the habitats at the elevation of 1212-1708 m, and slope of 31-49°, if elevation was above 1900 m, stability of oak-pine mixed forest would be sharply decreased.