Mass loss and nutrient release of forest litter during the freeze–thaw season could play an essential role in C and nutrient cycling in cold regions, but few studies in some key ecosystems have been available. In order to characterize litter decomposition during the freeze–thaw season in a subalpine forest region of western China, a field experiment using the litterbag method was conducted on the decomposition of foliar litter of two dominant species, fir ( Abies faxoniana) and birch ( Betula platyphylla) under their respective forests. Over the freeze–thaw season following leaf-fall, about 18% and 20% of mass, 13% and 14% of lignin, 30% and 26% of cellulose, 14% and 21% of C, 30% and 27% of N, 17% and 15% of P, and 17% and 13% of K were lost from fir and birch litters, respectively. The lost mass and components accounted for more than 64% and 65% of mass, 72% and 69% of lignin, 75% and 60% of cellulose, 49% and 59% of C, 56% and 71% of N, 62% and 37% of P, and 38% and 37% of K in 1 year net loss rate of fir and birch litter, respectively. In addition, the loss of mass, lignin, cellulose and component bio-elements during the freeze–thaw season correlated closely with the initial substrate type and the levels of the individual bio-elements. The results demonstrated that litter decomposition during the freeze–thaw season contributes significantly to the first year decomposition in these subalpine forests.