In polar regions, the study of the mechanical behavior of snow under compression is of great significance for the construction of snow runways and snow roads. This paper systematically investigates the microstructural evolution and macroscopic mechanical properties of snow under compression. First, triaxial compression tests were conducted to study the macroscopic mechanical behavior of snow. Subsequently, CT scans were conducted on samples at different loading stages to observe changes in the microstructure of snow. Additionally, a grain segmentation algorithm based on curvature and skeletonization was proposed to analyze the macroscopic mechanical properties of snow in relation to changes in the number and area of ice bonds. The results indicate that the snow loading process can be divided into two stages: the initial loading stage and the linear hardening stage. During the initial loading stage, the microstructure and ice bond area change little, while in the hardening stage, the ice bond area decreases significantly, leading to a lower tangent modulus. Horizontal ice bonds break more easily than vertical ones, causing increased anisotropy during loading. Based on the above analysis, we further investigated the mechanical properties of snow under different densities and loading rates. This study provides a microscopic explanation snow's macroscopic mechanical behavior, enhancing our understanding of its macroscopic mechanics, and contributes to the development of snow constitutive models based on microstructural evolution.