Microplastics (MPs; < 5 mm) have become one of the most prominent global environmental pollution problems. MPs can spread to high altitudes through atmospheric transport and can be deposited by rainfall or snowfall, potentially threatening the structure and function of natural ecosystems. MPs in terrestrial and aquatic ecosystems alter the growth and functional characteristics of organisms. However, little attention has been given to the possible harm associated with MPs deposited in snow, particularly in the context of global climate warming. MPs collected from surface snow in the Inner Mongolia Plateau, China, were used for quantitative analysis and identification. The results showed that MPs were easily detected, and the related concentration was approximately 68 ± 10–199 ± 22 MPs·L⁻¹ in snow samples. Fibers were the most common morphology, the polymer composition was largely varied, and the abundance and composition of MPs were linked to human activity to a great extent. High-throughput sequencing results showed that the composition and abundance of microorganisms also differed in snow samples from areas with different MP pollution characteristics, indicating a considerable difference in microbial functional diversity. MPs may have an interference effect on the individual growth and functional expression of microorganisms in snow. In addition, the results showed that functional living areas (e.g., landfills and suburban areas) in cities play an important role in the properties of MPs. For instance, the highest abundance of MPs was found in thermal power plants, whereas the abundance of polymers per sample was significantly lower in landfills. The MP contaminants hidden in snow can alter microbial structure and function and are therefore a potential threat to ecosystem health.