[Objectives] The availability of food resources is a key limiting factor of wildlife survival. Therefore, determining the competition status of sympatric species in relation to such resources is important for understanding their ecology and conservation requirements. The aim of this study was to analyze the competition status of sympatric Red Deer (Cervus elaphus) and Chinese Goral (Naemorhedus griseus) regarding diet composition and adaptability in Saihanwula Nature Reserve. [Methods] Using microscopic analysis of fresh fecal samples collected from August 2019 to July 2020 (Fig. 1), trophic niche width and overlap were calculated based on the diet composition of Red Deer and Chinese Goral. Significance tests for inter-seasonal and inter-species diet composition were carried out using a non-parametric Kruskal-Wallis model. [Results] The results showed that Red Deer fed on 48 plant species from 22 families in summer, and Chinese Goral fed on 31 plant species from 15 families. In winter, Red Deer fed on 32 plant species from 17 families, and Chinese Goral fed on 23 plant species from 13 families (Table 1). The frequency of each diet item varied significantly by season (Red Deer: χ2 = 46.6, df = 5, P < 0.01; Chinese Goral: χ2 = 17.4, df = 3, P < 0.01) (Fig. 2), and the trophic niche widths were greater for Red Deer than Chinese Goral in summer (Levin’s index of 13.71 and 5.34, respectively) and winter (Levin’s index of 11.08 and 4.02, respectively). The two species had a large dietary overlap (85.4% in summer, 77.6% in winter), and the trophic niche and diet diversity indices in summer were all significantly higher than those in winter (Table 2). [Conclusion] The results indicate that Red Deer are more adaptable to seasonal changes in food resources, although Chinese Goral may also adjust their feeding strategies. Given the wide distribution range and large population size of Red Deer, it is recommended that more conservation efforts be focused on Chinese Goral and their habitats.