Refined evaluation of ecosystem service functions in deep valleys in high mountain areas is an important means of precise protection of ecosystems. As the population continues to increase, human needs and demands on ecosystems continue to increase, and deep valleys in high mountain areas with good ecological integrity face the risk of development, it is urgent to balance protection and development and carry out precise protection of ecosystems. Based on the principles of typicality, specificity, feasibility and sustainability, this paper constructs an evaluation system for the ecosystem service function of the alpine deep valley area, consisting of 12 indicators from four aspects: Regulating functions, Provisioning functions, Supporting functions and Cultural functions. The Entropy Weight method was used to assign the weights of the relevant indicators in a hierarchical manner, and to complete the evaluation of the importance of ecosystem service functions and the importance zoning of the southeastern Tibetan Plateau. The results showed that: the importance of the ecosystem service functions of the Southeast Tibetan Plateau gradually decreases from southwest to northeast; the extremely important area is mainly distributed in the forest ecosystems with good originality and integrity in the south, accounting for 2.61% of the total area of the region, which needs to focus on ecological protection; the slightly important area is mainly distributed in the northern high altitude area with low vegetation cover and weak soil and water conservation capacity and grassland ecosystem, accounting for 58.89% of the total area of the region, which can be prioritized for development. The results of the study provide new ideas for precise protection of ecosystems and resolution of conflicts between ecological protection and development, as well as for the planning of functional areas for ecosystem services in deep valleys of high mountains, and also provide scientific references for regional sustainable development.