During the establishment of the Three-Rivers-Source National Park, herdsmen play a crucial role, and changes in their livelihoods and behavior significantly influence the park construction's effectiveness and sustainability. The article selects Three-Rivers-Source National Park as the research area and uses DID model and logistic regression model to systematically explore the relationship between national park construction and the livelihood outcomes and behavioral adaptability choices of herdsmen. The study found that: (1) while the construction of the Three-Rivers-Source National Park somewhat restricts the overexploitation of traditional livelihood resources by herdsmen, it also fosters ongoing enhancements in their livelihood standards; (2) Herdsmen's adaptive livelihood choices exhibit clear transitional traits in line with the park's construction, evolving from a phase of passive adaptation during the pilot phase to one of active endorsement during the formal establishment of the Three-Rivers-Source National Park; (3) In the construction process of Three-Rivers-Source National Park, herdsmen with high human capital, high per capita disposable income, and low proportion of animal husbandry income have shown a more proactive willingness to support their livelihood behavior adaptability choices.