Acid-soluble extractive (ASE) and acid-insoluble residue (AIR) are two essential components in foliar litter, and play an important role in the litter decomposition. Changes in ASE and AIR concentrations are not only one of crucial processes in litter decomposition, but also run the process of mineralization and humification of organic materials in litter to a large extent. Theoretically, ASE and AIR concentrations in litter vary with tree species, precipitation, soil temperature and moisture, and other biotic and abiotic factors. In the alpine forest ecosystem, the interception of canopy on snow accumulation and the effects of canopy shading on snow ablation in winter often create a snowpack gradient on the forest floor between the center of a gap and under the forest canopy in snowy season, and in turn might give strong effects on the dynamics of ASE and AIR in litter inside and outside of the canopy gap. As yet, little information has been available on the effects of snow cover on ASE and AIR concentrations in litter at different critical periods. Therefore, litterbags with foliar litter of birch (Betula albo-sinensis), cypress (Sabina saltuaria), larch (Larix mastersiana), fir (Abies faxoniana), willow (Salix paraplesia), and azalea (Rhododendron lapponicum) were placed on the forest floor along snow over gradients (deep snow, medium snow, thin snow and none snow) created by forest gap, canopy edge, expanded edge and closed canopy in three alpine forests of eastern Tibet Plateau. The litterbags were sampled at the stages of snow formation, snow cover and snow ablation from October 2012 to April 2013, and the concentrations of ASE and AIR in sampled litter were measured in time. Meanwhile, the LCI (Lignocellulose index) was also calculated. Over the first winter of litter decomposition, the absolute ASE concentration in foliar litter continued to decline as litter decomposition proceeded regardless of plant species, while AIR concentration in foliar litter increased except for birch leaf litter. Snow cover gave significant (P<0.05) effects on ASE and AIR concentrations in foliar litter at snow cover and ablation stages regardless of plant species. Absolute AIR concentration in cypress, birch and willow litter beneath deep snowpack increased more significantly in comparison with those beneath shallow and no snowpacks. The response of ASE concentration in foliar litter to snow cover depended on plant leaf forms. The maximum changes of absolute ASE concentrations in broadleaf litter were found beneath the thin and no snowpacks, whereas those in needle litters showed the opposite trend. After a snowy season, LCI, an index of indicating the relative changes of ASE and AIR concentrations in foliar litter increased significantly (P<0.05) regardless of plant species. The effects of snowpacks on LCI in foliar litter were observed mainly at the stages of snow cover and ablation, and the foliar litter of cypress, fir and willow had the highest LCI beneath the deep snowpack. In addition, the statistical analysis revealed that the wintertime dynamics of ASE and AIR concentrations and LCI in foliar litter were influenced significantly (P<0.01) by litter quality determined by plant species. The results here imply that the changes of winter snow cover pattern as affected by winter warming and forest gap regeneration will give a strong effect on the dynamics of ASE and AIR concentrations and the relative ratios of ASE to AIR in foliar litter, and in turn alter the process of mineralizaition and humification of organic materials in the alpine forest ecosystems. However, the effects of snow cover on the dynamics of ASE and AIR concentrations also depend on litter quality related with plant species.