Foraging represented the primary energy acquisition strategy for animal survival and reproduction, with behavioral plasticity enabling dietary adjustments to fluctuating food availability. The white-headed langur (Trachypithecus leucocephalus) is a rare and endangered primate endemic to China, which is only distributed in karst habitats. Due to human disturbance and destruction, the habitats of the white-headed langur are seriously fragmented and degraded, which will inevitably increase the survival pressure faced by the white-headed langur. In the past, the researches on the foraging behavior of this species mainly focused on the population level, and there was a lack of researches at the individual level, such as feeding duration and feeding rate. Therefore, it is of great significance to study the foraging behavior of white-headed langurs to better understand their adaptation mechanisms to environmental changes. From July 2019 to August 2020, we studied a habituated group of white-headed langurs in Guangxi Chongzuo White-headed Langur National Nature Reserve. Based on individual identification, we employed focused sampling and continuous recording methods to collect and analyze white-headed langurs foraging behavior data to investigate the foraging strategies. The results showed that the white-headed langurs consumed 40 plant species (27 families, 35 genera), including 18 tree species, 11 shrubs, 9 lianas, 1 herb, and 1 parasitic plant. Folivorous behavior dominated foraging time (75% of total observation periods), with young leaves constituting the majority (54.4%) compared to mature leaves (20.6%). The remaining dietary components comprised fruits (8.3%), flowers (3.8%), and other plant parts (12.9%). However, the feeding proportions of white-headed langurs on different plant parts changed significantly across seasons. In the dry season, the proportion of flowers and other parts in their diet was significantly higher than in the rainy season (flowers: 8.2% vs 2.2%; other parts: 35.6% vs 4.3%), whereas the proportions of young leaves and fruits were significantly lower (young leaves: 31.3% vs 63.1%; fruits: 4.8% vs 9.6%). In addition, white-headed langurs fed in clusters, forming feeding groups of varying sizes. Feeding clusters comprising 2-4 individuals accounted for 74.7% of all group feeding events. Significant differences occurred in fruit consumption duration across different cluster sizes. Fruit intake duration showed positive correlation with cluster size. These findings reveal that white-headed langurs ensure their own survival and perpetuation by flexibly modifying their foraging strategies in response to fluctuations in the availability of food resources. This study advanced understanding of limestone habitat adaptations in this endangered primate, providing critical scientific data for conservation strategies.