The construction of national parks is a natural protection public welfare construction project, which involves typical multi-participant and incentive compatibility. The key to it is to coordinate all relevant interest groups to fully reach a consensus. This study based on the characteristics of China's national park system construction, from the perspective of social impact assessment, taking the cross-regional construction of Gaoligong Mountain National Park jointly built by Yunnan and Xizang as an example, evaluating in advance the social benefits and social effects of national park construction. In order to objectively analyze the possible positive and negative effects, stakeholder attitudes, social impact, and the potential social risks. Also, this paper discusses the content and index system of social impact assessment in line with the establishment of cross-regional national parks, to provide scientific theoretical methods and case references for the subsequent construction of cross-regional national parks from the perspective of social impact. By the analysis and evaluation of the social impact, social adaptability, social risk and sustainability of the establishment of Gaoligong Mountain National Park, the results show that the construction of this national park: (1) mutual promotes with stakeholders to a moderate degree, (2) is conductive to the overall coordination and sustainable development of regional ecology, economy and society, (3) has strong adaptability with the local social environment, (4) takes low risks, and the relevant general and small social risk factors can be effectively resolved by adopting customized avoidance and preventive measures. (5) The sustainability of construction and social effect of national parks can be enhanced by developing scientific and reasonable social management programs. In brief, the establishment of Gaoligong Mountain National Park has positive social impacts, controllable social risks, stakeholder support, more advantages than disadvantages, and the project can be implemented successfully. This newly established social impact assessment system for cross-regional national parks is in line with the actual construction of national parks in China, which also has strong theoretical guidance and practical promotion functions. In the following application, we should take notice of diversity of evaluation objectives, multi-levels and differences of social factors, and emphasize stakeholder analysis and social risk assessment. Meanwhile, this social impact assessment system may promote the multi-level adjustment and optimization of future policies associated with protection and management.