Abstract: Soil fauna plays an important role in plant litter decomposition. To examine the decomposition mechanism of coniferous leaf litter along the elevation gradient in Wuyi Mountain, we applied litterbag method and naphthalene treatment to study the decomposition function of soil fauna and dynamic decomposition of coniferous leaf litter along altitude from April, 2007 to April, 2008. The results showed that the situation of decomposition rates of coniferous leaf litter in different kinds of bags without naphthalene treatment in evergreen broadleaf forest is that the rate of coarse size bags is 133 times more than that of medium size bags, and 1.54 times more than that of fine size bags. In alpine meadow, the coniferous leaf litter decomposition rate of coarse size bags is 1.12 times more than that of medium size bags, and 1.22 times more than that of fine size bags. Soil fauna plays a significant role in plant litter decomposition. The contribution rate of soil fauna in evergreen broadleaf forest is 32 %, and it is only 5 % in alpine meadow. One of the important reasons about the low decomposition rate is that the decreased function of soil fauna. With the increase of the altitude and the decrease of temperature, the kind of soil fauna is decreasing, the ability of soil fauna’s act is turning low, and the decomposition rate of the coniferous leaf litter is turning low. The decomposition process of leaf litter was synthetically influenced by litter quality, the kinds and quantity of soil fauna, temperature and rainfall.