Given the ongoing global decline in biodiversity, species reintroduction has become an important strategy for the conservation of endangered wildlife. P & egrave;re David's deer (Elaphurus davidianus), a historically extinct-in-the-wild species successfully reintroduced in China, represents a useful model for evaluating ecological responses following reintroduction into different habitats. Increasing evidence suggests that fecal microbiota can serve as a non-invasive indicator of host-associated microbial communities and their variation under different conditions. In this study, we investigated the fecal microbiota of a reintroduced population in the Daqingshan National Nature Reserve (Inner Mongolia). A total of 90 fresh fecal samples were collected between December 2021 and October 2023 across different seasonal periods. High-throughput 16S rRNA gene sequencing was used to characterize microbial community structure, and comparative analyses were conducted alongside published datasets from populations in Beijing and Shishou. The results revealed significant seasonal variation in microbial community composition and diversity, with distinct clustering of rainy, dry, and transitional (October) samples. Several taxa exhibited differential enrichment between seasons, suggesting temporal shifts in microbial community structure. A comparative analysis with other populations (Beijing and Shishou) revealed differences in microbial composition at broad taxonomic levels, suggesting potential variations related to regional environmental conditions, diet, and management practices. Overall, the observed patterns are consistent with seasonal variation in plant resource availability and highlight the potential influence of geographic context on microbial community structure. This study provides baseline data on the fecal microbiota of P & egrave;re David's deer in a semi-arid steppe environment and the potential indication of host suitability from the perspective of the microbiome.