Soils in subalpine and alpine ecosystems during winter experience extensive snow cover, freezing, thawing, and freeze-thaw cycle with air temperatures fluctuating above and below 0 ℃. Such conditions have profound repercussions on soil nutrient availability, microbial biomass, and enzyme activity in subalpine and alpine ecosystems during winter, yet systemic studies of these ecosystems are lacking. In order to deeply understand winter ecological processes in the subalpine and alpine forests of western Sichuan, three fir (Abies faxoniana) forests including primary fir forest at 3582 m altitude, fir and birch mixed forest at 3298 m altitude, and secondary fir forest at 3023 m altitude were chosen as study subjects. Soil was collected at different stages: at the onset of the soil freezing period, the soil frozen period, the soil thawing period, and the growing season from November 2008 to October 2009. Concentration of dissolved carbon and nitrogen, NH₄⁺-N, and NO₃^--N were measured in each soil sample. Compared to the growing season, the content of measured nutrients was relatively high during winter in all sampled forests. Moreover, the dynamics of the measured soil nutrients changed with the processes of the soil freeze-thaw cycle. In the soil organic layer, the amount of dissolved carbon and nitrogen, NH₄⁺-N, and NO₃^--N significantly increased followed by a decrease in both the onset of the soil freezing period and the soil thawing period, whereas they showed little change in the soil frozen period, except for NH₄⁺-N. In the mineral soil layer, the content of the measured nutrients also significantly increased and then decreased with the onset of the soil freezing period. However, the content of the dissolved nitrogen, NH₄⁺-N, and NO₃^--N visibly increased in the soil frozen period, reaching a peak in the soil thawing period. Additionally, the interaction of the altitude and soil layer affected the amount of dissolved carbon and NO₃^--N. Correlation between the concentration of soil nutrients and soil temperature varied with the altitude. The results suggested that the seasonal freeze-thaw period is a crucial stage for ecological processes in the soil, and the soil freeze-thaw pattern significantly affects the dynamics of soil nutrients in the subalpine and alpine forests of western Sichuan.