With a warming climate, cold regions ecosystems undergo significant ecological change such as permafrost thawing, and shifting ecosystem boundaries including the spread of canopy-forming shrubs into tundra communities (term as shrubification) over past decades. Recent researches have documented shrub expansion around the cold regions using repeat photography, long-term ecological monitoring and dendrochronology, which could cause major modification to the diversity and functioning of ecosystems. Interactions between shrub and snow are becoming the important parts in cold region hydrological research. The findings can be synthesized as: (1) impact of shrubs on snow accumulation and ablation processes; (2) adaptation of the physiological and ecological characteristics of shrub to snow cover; (3) influences of snow-shrub combination climate systems on permafrost changes and carbon emissions in the permafrost and seasonal frozen regions. Studies indicate that changes in the density or extent of shrub cover in tundra ecosystems could modify snow distributions, nutrient inputs, carbon stores, surface albedo and associated energy fluxes, potentially creating positive feedbacks to climate change. In the winter, snow trapping can insulate soils by trapping heat, and has been proposed as a positive feedback mechanism for promoting the expansion of shrubs in cold regions. During spring, shrubs that extend above the snow alter the albedo and accelerate local snow melt. In summer, shrubs shading decreases soil temperature under canopies. In winter, snow in shrub patches is both thicker and a better thermal insulator per unit thickness than the snow outside of shrub patches. As a consequence, winter soil surface temperature is substantially higher, and a condition is formed that can promote greater winter decomposition and nutrient release, thereby providing a positive feedback that could enhance shrub growth rate. In order to project future rates of shrub expansion and snow cover change and understand the feedbacks to ecosystem and climate change processes, future research concerning interaction between shrubs and snow should: (1) estimate accurately the distribution of snow cover in the shrub areas; (2) take shrub-snow-permafrost as a continuous system; (3) develop hydrological model coupling with shrub-cover and snow cover in cold regions.