Ecotone system often exhibits relative more complicated environment, which could provide relative more habitats for creatures, and displays relative higher biodiversity compared with the near ecosystems. Subalpine forest-pasture ecotone is an important ecotone system in western mountain area of upper Yangtze River, and does the crucial functions in regulating regional climate and conserving soil and water. Soil fauna, the key component in an ecosystem, plays an essential role in material cycling and energy flow in the ecosystem. To explore soil fauna diversity in pasture-forest ecotone disturbed by grazing, the structure and diversity of soil fauna communities were investigated in the typical subalpine forest-pasture ecotone of Miyaluo natural reserve in western Sichuan from August 2008 to August 2009. Five representative plots including coniferous forest, broadleaf forest, shrub land, dwarf shrub land and grassland were sampled along the disturbance gradient in the forest-pasture ecotone. There were 200 meters with horizontal distance between the two sampled plots. A total of 49837 individuals were detected under the five sampled micro-systems from meadow to forest system in the ecotone, which belonged to 7 phyla, 16 classes, 33 orders and 126 groups. Including others, there were 35688 individuals belonged to Nematoda, which accounted for 84.08% of the total individual density, indicating that Nematoda could be the only dominant group in these groups. The density of Enchytraeidae, Eutardigrada and Harpacticoida accounted for 4.14%, 247% and 5.52% of total individual density, respectively. These population could be defined as the common groups in this forest-pasture ecotone. The remaining 122 groups of soil macro，meso and micro fauna could be defined as the rare groups. From the meadow to the coniferous forest in this ecotone system, the diversity of soil fauna communities decreased with the increase of disturbance intense. In the disturbance conditions, individual density of soil fauna was gradually decreased with the increase of grazing intense while the group richness was highest in shrub land compared with the others. The individual densities of the dominant groups were lowest in grassland compared with the other sampled plots, although they gradually increased from grassland to forest regardless of soil fauna body size. There were obvious variations among the dominant groups of the soil fauna with different body size, especially in dominant groups of macrofauna. The Shannon-Wiener and density-group indices were also gradually increased from grassland to forest. The Wilson-Shmida index indicated that species replacement rate was not significant among the sampled plots, but the minimum biomass of soil macro-fauna was observed at grassland, the maximum at broad-leaf forest. The density, group and biomass of soil fauna showed an obvious seasonal dynamics pattern. CCA analysis indicated that there was a significant correlation between litter thickness, pH and soil meso-micro fauna, but the other investigated soil factors were slightly related to meso micro fauna. The results suggest that there was a high diversity of soil fauna in the subalpine Pasture-forest eotone of Western Sichuan, and the structure and diversity of soil fauna community were varied under different grazing disturbances in this ecotone system.