A four-season investigation was conducted on the soil animals in the litter layers and soil layers depth of 0-15 cm of Castanopsis fargesii forest at Tiantong, Zhejiang province during September, 2003 and July, 2004. The litter layer includes fresh litter layer (L), fermentation layer (F) and humus layer (H).Soil animals amount to a total of 32, 657 in number, including macrofauna, mesofauna and wet types, falling into 10 classes and 27 groups respectively. For soil macrofauna, the dominant groups are Coleoptera, Hymenoptera and Blattoptera, while for mesofauna, they are Acarina and Collembola and for wet type ones, Nematoda. The results of the investigation indicate that: (1) the group numbers and density are all greater in the litter than in the soil depth of 0-15 cm; (2) the vertical distribution of soil animals in the litter differs from that in the soil, the group numbers in the former tend to increase gradually from top to bottom,with those in bottom humus layer the largest; altogether 18 groups are found in it;large numbers of individuals are seen in the middle fermentation layer and in the bottom humus layer, with those in the former greater, both accounting for 77.04 % of the total; (3) the DG index (density-group index) reveals a seasonal change of soil animal community diversity as autumn ＞spring＞winter＞summer; (4) the vertical distribution of dominant groups varies with seasons in a regular manner, thus influencing the seasonal change of the vertical distribution of the entire community.