Abstract: A field experiment was conducted using the litterbag method to quantify the contribution of soil fauna to litter mass loss of Salix paraplesia, Sabina saltuaria, Betula albosinensis and Abies faxoniana during different key periods of the decomposition process of the first year (from November 2011 to October 2012). The results showed that the mass loss rate showed S. paraplesia > B. albosinensis > A. faxoniana > S. saltuaria, and the rate in the growing season was greater than in the freezethaw season. The contribution rate of soil fauna to the mass decomposition displayed as S. saltuaria (26.7%)>A. faxoniana (18.8%) > B. albosinensis (15.7%) > S. paraplesia (13.2%), which was higher in the freezethaw season than in the growing season for litter of B. albosinensis and A. faxoniana while vice versa for litter of B. albosinensis and A. faxoniana. The contribution of soil fauna was mainly related to organic C, P and N/P in the freeze-thaw season, while N,  C/N,  lignin and lignin/cellulose in the growing season.