Litter decomposition is a key process in nutrient cycling in forest ecosystems. Mixed leaf litter from different tree species is known to decompose faster and harbor greater microarthropod diversity than single leaf litter. However, studies on litter decomposition are limited mostly to leaf litter. On the forest floor, leaves are always mixed with twigs. The objectives of this study were to determine (1) whether mixed leaf and twig litter promotes decomposition more than monotype litter and (2) whether the litter mixture increases the abundance and diversity of soil organisms. Litterbag experiments were conducted using litter of Cinnamomum camphora and Quercus crispula. For both tree species, the leaf and twig litter mixture promoted the decomposition rate compared with monotype litter. The microarthropod abundance was not affected significantly by the mixing, whereas there was a significant increase in the fungal/bacteria ratios and moisture contents of leaf in mixed litter compared to monotype leaf litter. This suggests that the decomposition rate of the litter mixture was affected by the moisture content of the litter.