The notable differentiation in ecosystem gradients in the Yarlung Zangbo Grand Canyon basin critically influences the regional ecosystem patterns and functional stability. However, research on the differences in the vertical distributions of landscape patterns and ecosystem service functions between the southern and northern slopes and their coupling relationships remains insufficient. Based on published datasets, principal component analysis was employed to integrate 9 landscape pattern indices, thereby constructing a comprehensive landscape fragmentation index (LFCI). The Integrated Valuation of Ecosystem Services and Trade-offs model was applied to calculate habitat quality, carbon storage, water conservation, and soil retention to assess the multiple ecosystem service function (MESF). The transect method was adopted to investigate the vertical differentiation of landscape patterns and ecosystem service functions. The results revealed the following: (a) The degree of fragmentation in landscape patterns was relatively low, whereas fragmentation in ecosystem service functions was relatively high. From 2000 to 2023, the LFCI remained stable; however, the MESF tended to decrease. (b) The LFCI increased with altitude, whereas the MESF decreased, and both indices remained stable in high-altitude snow-covered areas. The southern slopes presented higher fragmentation levels and lower ecosystem service functions than the northern slopes. (c) A positive correlation existed at low altitudes (<3,500 m); conversely, a negative correlation emerged at midaltitudes (3,500 to 5,000 m). In high-elevation (>5,000 m) snow-covered regions characterized by snow-dominated landscape patterns, there was evidence of positive synergy. This study enhances our understanding of alpine landscape-function coupling and offers scientific groundwork to support regional ecological protection and sustainable development.