Population dynamics of soil microbiota and nematodes during decomposition process of mixed leaf litters were investigated based on field study in Xishuangbanna tropic rainforest and simulated investigation indoors. We designed litterbags with coarse mesh size of 1 mm and fine mesh size of 100 μm to restrict access by most soil macrofauna and mites, respectively, to estimate the effects of different soil fauna components on litter decomposition. In the indoors experiment, sterilization and inoculation were adopted to investigate the different effects of nematodes and microbiota on leaf litters. The results showed that microbial basal respiration declined during decomposition and positively correlated with the decay rate. The dynamics of microbial biomass and bacterial and fungal biomass measured from substrate-induced respiration (SIR) kept to some succession route during litter decay. Commonly, the dynamic of microbial community followed “double peak” route and presented distinct succession trend with gradually improvement of the carbon utilization of microbe, when prey stress of soil fauna that participated in the decay process existed. Otherwise, microbial community conformed to “single peak-decadency” dynamic model, microbial biomass decreased sequentially and the carbon utilization of microbe declined as well as no prey stress occurring. On contrary to microbial “double peak” dynamic model, the development of soil fauna accorded to “single peak” pattern. The preyor and preyed had some ebb and flow connection between under “prey- excitation” effect which related to the intension of prey stress. “Double peak” dynamic model of microbe accelerated the decay process in some extent.