In this experiment carried out in 1998 when the Three Gorges Project was about to start,soil faunae in different habitats and at different altitudes were investigated in the Three Gorges Reservoir Region,including Zigui County,Wanxian County and Shennongjia region.Results show that in the region,Nematoda was the predominant group,and Acarina,Collembola,Tardigrada and Harpact icoida were common groups.Soil faunae under different vegetations at the same location displayed certain similarity and difference as well.Correlation tests demonstrated that altitude and habitat had little effect on the correlation between the numbers of soil arthropod individuals and groups.It was also discovered that the lower the more favorable the habitat (altitude and vegetation),the higher the biodiversity index.Comparison between communities in similarity showed that fauna communities under similar vegetations at the same elevation were quite high in similarity.In Zigui Country,the numbers of Nematoda,Acarina and Collembola individuals were not much affected by habitat and elevation,while in Wanxian Country,the numbers of Acarina and Collembola were by elevation.In Shennongjia region,distribution of Nematoda varied significantly with vegetation.Acarina and Collembola were widely distributed in various soil layers under different vegetations,whereas the number of Acarina in the litter layer varied significantly with habitat and elevation.