The coniferous and broad-leaved mixed forest in Jiajin Mountain, Sichuan Province was selected to analyze the relationship between the species diversity of the alpine vegetation community and the aboveground and underground productivity and the response of the two to different levels of grazing disturbance by using typical sampling method and DCA two-dimensional ordering. The results showed that:(1) there were 172 species of trees, shrubs and herbs belonging to 55 families and 117 genera in the coniferous and broad-leaved mixed forest communities of Jiajin Mountain. The dominant species in the tree layer and shrub layer changed little under various levels of disturbance, and Acer caudatum var. prattii and Fargesia spathacea always occupied the first place, while the dominant species in herbaceous layer changed greatly; (2) With the increase of the grazing disturbance (from Ⅳ to Ⅰ), the important value of annual herbs increased, while that of perennial herbs decreased, and that of gramineous grasses decreased. The ratio of underground to aboveground biomass in herbaceous layer decreased significantly; (3) The species diversity level of tree, shrub and herbs was the highest under the level IV and the lowest under the level I; (4) The results of redundancy analysis showed that the species diversity index of shrubs and herbs (except Pielou evenness index J_sw) was positively correlated with the biomass of each layer, and the diversity indexes of tree layer were positively correlated with the aboveground and underground biomass of shrub layer and litter fall; (5) The proportion of saplings under level IV was significantly higher than that under other levels. But there were almost no dominant saplings in the forest under severe disturbance (level I), so the regeneration ability of the community was the worst. It is recommended to set the management measures for Ⅰ and Ⅱ (that is, within 2000 m from the pig farm) to grazing prohibition or rotation grazing, and focus on maintaining the growth of saplings of Acer caudatum var. prattii and Betula utilis to promote the regeneration of vegetation communities.