Aiming at the questions of optimal allocation of target ET based on R-ET (Runoff-Evapotranspiration) water resources management model for the Yellow River Basin, this paper constructed 4 objective functions and constraint condition based on Multi-Objective Genetic Algo - rithm, including the functions of water resources control, ET control, irrigation water guarantee and Eco & life water guarantee, and design pa - rameters of MOGA to solve the optimal allocation questions. Ordos was taken as the research case, according to calculation of 5 water utilization schemes in 2015, the irrigation farmland target ETIta accounts for about 36% of the total target ETta, the residential and industrial land ETJta accounts for about 20%, uncontrolled target ETNta accounts for about 50%. Meanwhile, actual ET distribution ratio is as follows: Uncontrolled ETN occupies 64.4% of the total actual ET, irrigation farmland ETI occupies 33.6% the residential and industrial land ETJ occupies 2%. The comparison find that to achieve target ET, the reduction and control should focus on uncontrolled ET and the irrigation farmland ET. According to the actual situation in the study area, this paper put forward the control key of the sectional target ET and related measures, and lays the foundation of the necessary for the implementation R-ET water management for the Yellow River Basin.