Wild boar (Sus scrofa) is one of the omnivorous animal species with the widest distribution worldwide. Analyzing the dietary habits of wild boars during winter can directly reveal their food sources during the food scarcity period. The adaptive potential of the host gut microbiota is closely related to and interacted with dietary habits. In this study, DNA metabarcoding technology and high-throughput sequencing technology were used to analyze the dietary habits and gut microbial features of wild boars during the winter food scarcity period in the southern part of the Xiaoxing’an Mountains, and to explore their interactions. The results showed that the plants consumed by wild boars in winter belonged to 42 orders, 80 families, and 165 genera. The main food sources included 18 plant specie, including Magnoliopsida, Equisetum hyemale, Gueldenstaedtia verna, Bistorta vivipara, Rosa beggeriana, and Mazus sunhangii. A total of 531584 valid sequences were obtained using high-throughput sequencing technology, and microorganisms belonging to 36 phyla, 255 families, and 564 genera were identified. At the phylum level, Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria were the dominant bacterial phyla. At the genus level, the dominant genera included 15 genera such as the unclassified genus under the family Muribaculaceae (order Bacteroidales), Treponema, Escherichia Shigella, and Prevotellaceae_NK3B31_group. There was a strong correlation between the gut microbial community of wild boars and their dietary habits. The relative abundance of gut microbial genera in wild boars was significantly positively correlated with the relative abundance of consumed plants. In the PICRUSt2 functional prediction, the functional abundance of carbohydrate metabolism was the highest, and the carbohydrate metabolism capacity of the microbiota was significantly positively correlated with the proportion of plant carbohydrates consumed by wild boars. By investigating the main food types of wild boars and the composition and function of their gut microbiota during the winter food scarcity period, our results provide a reference for further understanding the mutual relationship between the gut microbial community and dietary habits of wild boars.