[Objective] Based on the regional key ecosystem services, the regional ecological function regionalization of Tibet Autonomous Region was studied to provide basis for the regional comprehensive cognition and spatial comprehensive management of the plateau ecosystem. [Methods] With the support of GIS technology, the index system of ecological function partition in Tibet was constructed based on the regional key ecosystem service. Using the self-organizing feature mapping (SOFM) clustering grid cell index, the boundary of ecological functional area was determined by merging small watershed cells. [Results] ① The ecosystem service function index exhibited a notable decreasing gradient from the southeast to the northwest. ② According to the landscape aggregation index of each classification grid, the optimal classification number was five. ③ The fragmented five clustering results were finally divided into five ecological function areas after the merger of small watershed cells. [Conclusion] According to the characteristics of each regional ecosystem, the five ecological functional areas including: the ecologically fragile alpine desert grasslands in Northern Tibet, the animal husbandry surplus areas in Central Tibet region, the agriculture and animal husbandry product supply areas in East Asia tropical mountain coniferous forests, the water production areas in Southeast Asia tropical mountain coniferous forests, and the biodiversity protection areas in Southeast Tibet tropical seasonal rain forests.