The gut microbiota is a critical component in the modulation of host metabolism and the adaptation to environmental conditions. Its composition is significantly influenced by dietary intake and evolutionary genetics, making it a key factor in the survival and health of various species. This study delves into the gut microbiota and dietary habits of the Marco Polo sheep (Ovis ammon polii), across different seasons. The aim is to elucidate how the microbiota enhances the host's resilience to environmental stressors, thereby informing conservation strategies for endangered species. To achieve this, we collected 12 fresh fecal samples from the Marco Polo sheep during both the warm and cold seasons. Employing DNA metabarcoding and 16S rRNA sequencing, we comprehensively analyzed their dietary and gut microbial profiles. This approach allowed us to reveal the seasonal dynamics and understand how these dynamics affect the sheep's ability to adapt to varying environmental conditions. Our analysis reveals that the Marco Polo sheep have a wide dietary spectrum, consuming plants from 36 families and 57 genera. A notable difference in dietary composition was observed between the warm and cold seasons, with plants from the Rosaceae and Amaranthaceae families consistently predominating in their diet across both seasons. This consistency suggests a preference or necessity driven by nutritional needs or availability. The calculated nutritional niche width was 3.18 for the cold season and 2.94 for the warm season, indicating a broader nutritional niche in the colder period. This broader niche may reflect the sheep's adaptive foraging strategies in response to the scarcity of food resources during winter. Such strategies are essential for their survival, as they must maximize the utilization of available resources to maintain their health and energy levels. Significant seasonal variations were observed in both the α and β diversity of the gut microbiota, with strong correlations between dietary abundance and gut microbial composition. The gut microbiota of the Marco Polo sheep showed marked seasonal fluctuations that corresponded with dietary shifts. This synchronization suggests a dynamic relationship between diet and gut microbiota, where changes in diet directly influence the microbial community. Functional predictions of the gut microbiome indicated a substantial increase in the relative abundance of genes associated with ester compound biosynthesis, protein digestion, and metabolism during the cold season, a time of food scarcity. This adaptation likely facilitates enhanced nitrogen utilization and energy storage, improving the sheep's ability to withstand the harsh winter conditions. The ability to adapt their gut microbiota in response to dietary changes is a critical survival mechanism for the Marco Polo sheep. These findings deepen our understanding of the complex interactions between gut microbiota and their hosts in Plateau ecosystems. The insights gained from this study into the dietary and microbial strategies employed by the Marco Polo sheep to increase their resilience against environmental challenges are highly relevant for the conservation of endangered species in the context of environmental change.