[Objectives] Dietary research is a crucial component of conservation studies for endangered wildlife. Both Chinese Serow (Capricornis milneedwardsii) and Chinese Goral (Naemorhedus griseus) are class II national key protected wild animals in China. The winter season is characterized by harsh environmental conditions and scarce food resources, making the overwintering period a critical survival bottleneck for these two species. To clarify the winter dietary strategies and nutritional adaptation mechanisms of these sympatric species, this study was conducted in Hubei Dalaoling National Nature Reserve from November 2023 to March 2024. The specific research objectives are as follows:(1) To identify the winter food composition and plant category preferences of the two species; (2) To analyze the diversity of their winter diets and the degree of food niche overlap; (3) To explore the correlations of their foraging frequency with the nutrient components (crude protein, crude fat, crude fiber, crude ash) and tannin of food plants; (4) To provide targeted scientific support for the conservation and management of the two species by comparing their dietary differences and adaptive strategies. [Methods] On the basis of infrared camera monitoring data collected from 2019 to 2024, 20 sites with high occurrence frequencies of Chinese Serow and 9 sites with high occurrence frequencies of Chinese Goral were selected as survey locations. At each site, a transect approximately 2 km in length was established perpendicular to the contour lines, along which signs of activity of both species were recorded and fresh fecal samples (≤ 3 d old) were collected. For each fecal occurrence area, a 20 m × 20 m plot was centered on the location to collect plant species consumed by the two ungulates. Fecal microhistological analysis (10 × 10 magnification) was conducted to determine winter diet composition, and the frequency of occurrence (F) and relative density (RD) of each plant species in feces were calculated. Diet diversity was assessed based on the Shannon-Wiener diversity index (H^′), evenness index (J^′), and niche breadth index (B), while winter diet overlap between the two species was quantified by Pianka’s index (C). Nutritional components and tannin content of plants were determined strictly following national standard methods of the People’s Republic of China. Data analysis was conducted in OriginPro 2024 (Version 10.1.0.178), where one-way ANOVA was carried out to test differences in tannin content among plant species, followed by Tukey’s multiple comparison tests. Pearson correlation analyses and visualization were performed in R version 4.3.2 to examine relationships between winter feeding frequency and plant nutritional components. [Results] (1) Both species fed on 13 plant species belonging to 12 families in winter. The main winter food sources of Chinese Serow were Carex taliensis (17.05%), Elaeagnus lanceolata (12.54%), Dryopteris atrata (11.35%), and Pachysandra terminalis (10.37%); while the main winter food sources of Chinese Goral were C. taliensis (18.55%), Viburnum erosum (12.35%), Tripterospermum discoideum (9.31%), and P. terminalis (9.04%) (Table 2). (2) The categories of food plants for Chinese Serow in winter were in the order of shrubs (39.35%), herbs (22.09%), ferns (17.37%), lianas (14.95%), and mosses (6.26%); for Chinese Goral, the order was herbs (34.13%), shrubs (30.88%), lianas (14.81%), ferns (13.66%), and mosses (6.52%) (Fig. 4). (3) The winter food diversity of Chinese Serow and Chinese Goral was close (Shannon-Wiener index H′:2.23 vs. 2.25; Pielou evenness index J′:0.86 vs. 0.87; Simpson index B:8.3 vs. 8.42), and their food niche overlap was high (Schoener’s niche overlap index C = 0.88), indicating that intense interspecific competition may exist between the two species (Table 3). (4) The winter foraging frequency of Chinese Serow showed positive correlations with the content of crude protein, crude fat, and crude fiber in food (correlation coefficients R:0.42, 0.35, and 0.33 respectively, P < 0.05), but no significant correlation with crude ash or tannin content (P > 0.05). For Chinese Goral, its winter foraging frequency was positively correlated with crude protein, crude fat, and crude ash content in food (R:0.61, 0.59, and 0.45 respectively, P < 0.05), while no significant correlation was found with crude fiber or tannin content (P > 0.05) (Figs. 5 ~ 7). [Conclusion] The food plant species of Chinese Serow and Chinese Goral show a high overlap in winter. Regarding their foraging strategies, both species prioritize food accessibility over palatability in winter and give priority to ensuring a stable intake of protein and energy. The difference between the two species lies mainly in that Chinese Serow focuses more on the satiety provided by food, while Chinese Goral places a greater emphasis on the nutritional refinement of food.