Three croplands, which all are 5 meters long, at 5°, 15° and 25°slope gradients respectively, were selected in the hilly areas of Central Sichuan Basin in March and September 2010. The investigations were conducted to study the effects of slope gradient on soil fauna. The methods of Tullgren and Baermann were used to extract soil fauna from soil samples (0-15cm). A total of 11 657 individuals, belonging to 3 Phylum, 11 Classes, and 21 Orders, were extracted from the soil. The orders of Springtails, Mites, Tubificida and Nematode were the dominant groups of the soil fauna community in Hilly areas of Central Sichuan Basin. As slope increased, the taxonomic richness of soil fauna was not significantly changed in March (P>0.05), but increased significantly in September (P<0.01). The community density decreased significantly with the increasing of slope gradient in Mach (P<0.01), but increased in September (P<0.05). Diversity indexes fluctuated with slope gradient in March, as well as in September. The abundance of the major taxonomic groups varied in their response to slope increasing. The result of a principal component analysis (PCA) indicated that the community structures of soil fauna differed obviously among three slope gradients. Furthermore, the coefficients of Sorenson and Morisita-Horn suggested that effects of the slope on the taxonomic composition of soil fauna communities were stronger than on the abundance of the dominant groups in March, while the opposite was found in September. The results of ANOVA and t-test indicated that both slope and season had a significant effect on the diversities of soil fauna community and the abundance of the major taxa. However, the effects of slope on the diversity also varied with seasons. The results of our research suggested that the slope has a significant effect on the structure and diversity of soil fauna community and the abundance of major groups, which were also changed with the seasons. Further analysis showed that the soil water was the main reason for the differences among the community abundance and the soil erosion for the diversities of soil fauna.