Abstract:Due to the unique regional location and economic status of the Xiangjiang River Basin, and the pollution output of the upstream cities will affect the environmental performance of the downstream cities, therefore, this paper combines the undesired input-output to propose an improved RAM-Undesirable model and the Global-Malmquist index to measure the river environmental efficiency of the Xiangjiang River Basin urban cluster. The study finds that: (1) The overall environmental efficiency of the Xiangjiang River Basin urban cluster is relatively stable and gradually improved, but the regional differences are obvious. (2) Considering the undesired input can eliminate the error caused by the river fluidity and the initial water quality difference, thus reflecting more objectively the level of efficiency. (3) The efficiency changes and technological changes in urban rivers are unbalanced and there are complementary phenomena, among which technological change is the dominant factor leading to fluctuations in global Malmquist index.