Abstract: The ecological integrity theory recognizes the complexity of the ecosystem and emphasizes that in addition to protecting the structural and functional integrity of the ecosystem, large-scale natural landscape conservation should maintain the integrity of ecosystem biological components and ecological processes. Yellowstone to Yukon (Y2Y) is the largest surviving mountain ecosystem on earth, containing 11 national parks in its scope, which constitutes the largest group of national parks in North America. With the support and assistance of the Yellowstone to Yukon Conservation Initiative (Y2YCI) organization, Y2Y has influenced and strengthened the regional ecological integrity by establishing multi-scale protected areas and ecological corridors and stressing the protection of iconic species and ecosystem sustainability. In this process, the national park group has played the “leader” role in the regional ecological integrity protection, and promoted effective conservation of large-scale natural landscape in Y2Y. The protection and management of ecological integrity in Y2Y have provided a valuable reference for large-scale natural landscape with significant conservation value.