The national parks agglomeration in China is presently undergoing a pivotal phase of planning and construction. Synergistic development of nature-based tourism within the Qinghai–Tibet Plateau National Parks Agglomeration is essential for optimizing the spatial configuration of regional functions and substantiating the necessity of the agglomeration development of national parks. This study develops an assessment framework for the synergistic development of nature-based tourism based on the interconnection of elements. By constructing a model of nature-based tourism elements’ interconnections and employing social network analysis, it investigates the characteristics and status of synergistic development in nature-based tourism within the Qinghai–Tibet Plateau National Parks Agglomeration, while also proposing pathways for optimization. The findings reveal that: (1) By integrating multi-source heterogeneous data on resource complementarity, product connectivity, tourist source sharing, and information linkage, a robust assessment framework for the synergistic development of nature-based tourism in the national parks agglomeration was established. (2) The synergistic development of nature-based tourism within the national parks agglomeration on the Qinghai–Tibet Plateau demonstrates spatial heterogeneity. Shangri-La National Park and Qinghai Lake National Park serve as the core of the tourism flow network, whereas Mount Kailash National Park, Gaoligong Mountain National Park, and Pamir–Kunlun Mountains National Park exhibit the least favorable states of coordinated development. (3) Utilizing social network analysis, this study classified the national parks into core and peripheral positions within the nature-based tourism synergy network and proposed corresponding optimization strategies. The findings of this research contribute to optimizing the overall layout of the Qinghai–Tibet Plateau national parks agglomeration. Additionally, they provide theoretical and methodological references for the nature-based tourism synergistic development in other national park agglomerations.
