Against the backdrop of rapid industrial and economic advancement, aquatic ecosystems have endured significant degradation. As a novel mechanism for reconciling economic growth with water resource conservation, the river basin ecological compensation system hinges on the scientific formulation of compensation standards—an element critical to ensuring the sustainable development of river basins. This research focuses on the Hanjiang River Basin and the Middle Route of the South-to-North Water Diversion Project (MRO-SNWDP), aiming to determine ecological compensation standards by quantifying ecosystem service values (ESV) of compensation subjects and objects based on their intrinsic compensation relationships within the study area. The analysis calculates ecosystem service values across different land use types for each subject, revealing distinct patterns: in the upstream water source region of the Hanjiang River, the middle and downstream sections of the Hanjiang River, and the water-receiving area of the MRO-SNWDP, the land use types with the highest ecosystem service values are forests, forests, and farmlands, respectively. Functionally, regulating services contribute the most to overall value, while cultural services account for the least. To establish a reasonable compensation range, the study sets the lower bound using compensation amounts calculated from the perspective of traditional water diversion projects and the upper bound using amounts derived from a holistic basin-wide perspective. Based on this framework, the research concludes that the annual compensation the MRO-SNWDP water-receiving area should provide to the Hanjiang River Basin falls within the range of 22.959–27.841 billion yuan.