Decomposition of forest litter is one of the fundamental pathways for the flow of nutrients and energy in forest ecosystems and is an important component of the global carbon budget. Soil fauna plays a significant role in litter decomposition. However, the effect of soil fauna on alpine plant litter decomposition is poorly understood. In the present study, we have studied the dynamics of litter decomposition, nutrient-release, characteristics of the soil fauna community in litterbags, and the contribution of soil fauna in the process of litter decomposition of Rhododendron chrysanthum in the Betula ermanii forest in the Changbai Mountains. Nylon litterbags (15 cm×20 cm) with three mesh sizes (4 mm, 2 mm and 0.01 mm) were used in the experiment. Air-dried leaf litter ((8.00±0.01) g) was kept in the nylon bags and these were placed on the forest floor. The remaining litterbags of each type were taken on the 6th, 8th, 10th and 12th month after field placement. Soil macrofauna were picked by hand from the litterbags (4 mm and 2 mm mesh). Subsequently, mesofauna and microfauna were collected and separated by Tullgren methods. The litter was rinsed with deionized water to remove soil particles, oven-dried at 60℃ for 48 hours and weighed. Total nitrogen (TN), total carbon (TC) and total phosphorous (TP) contents were then tested. The results showed that the seasonal fluctuation and difference in decomposition rate of Rhododendron chrysanthum litter in the three different mesh size litterbags was very obvious during the first year. At the end of the first year, the accumulated rate of loss of litter in 4 mm, 2 mm and 0.01 mm size litterbags reached 34.19%, 31.22% and 25.45%, respectively. The decomposition rate showed significant seasonal differences. In general, the concentration of N increased and then declined during litter decomposition. A downward trend was generally found in the ratio of C/N in the remaining litter. Oribatida and Isotomidae played a dominant role in the decomposition process. In the first half of the year the involvement of soil fauna slowed down the decomposition process, when the environment was much colder and drier, however, with the rise in temperature and moisture in the following six months, the contribution rates of macrofauna and mesofauna to litter decomposition increased greatly. The contribution rates of soil fauna to the litter mass loss increased with time in the first year. During the 12 month decomposition, the contribution rate of both macrofauna and mesofauna to litter decomposition was 25.57%, of which the contribution rate of mesofauna to litter decomposition was 16.88%, much higher than the contribution rate of macrofauna to litter decomposition (8.69%). Mesofauna play an important role in the release of organic carbon. These results suggest that during the seasons of winter and spring there is an antagonistic effect of soil fauna on litter decomposition, whilst in summer and autumn, there is a synergistic effect from soil fauna on litter decomposition.