Community assembly and succession are focal points in community ecology research, serving as the fundamental drivers in shaping community structure and maintaining biodiversity. Thus, we conducted a series of experiments to explore the characteristics of plant communities and the spatial distribution patterns of plant functional groups (PFGs) in micro-patches, aiming to analyze the factors influencing plant community assembly and the potential relationships between plant community assembly and ecosystem stability. The results showed that the alpine K. pygmaea meadow was assembled by plant functional groups and constructive species in a mosaic distribution at a micro-scale. The characteristic plant communities of micro-patches were redistributed by polygonal landforms formed under the influence of abiotic environmental factors, resulting in a spatial distribution pattern with K. pygmaea as the primary micro-patches and various types of micro-patches as secondary. The dominance of K. pygmaea micro-patches was closely related to its physiological and biochemical characteristics, morphological structure, and resistance to interference. The micro-topography of cracks and collapse formed by freeze thawing could provide resource for the plant community migration at low grazing intensity, which could improve system functionality. However, these micro-topographies could increase the risk of ecosystem function decline under overgrazing conditions. Therefore, the formation of the mosaic distribution pattern of micro-patches in the Alpine K. pygmaea meadow was the result of the interaction of abiotic environment and biological factors. The mosaic distribution pattern was the basis for resisting certain interference intensity and maintaining the stability of system components.