Taking Chengde section of Luanhe River as the research object, the water quality of 9 sections was evaluated by single factor index method and grey correlation method. Then the control unit was divided according to the characteristics of water function area, and the water environment capacity of the research section was calculated by one-dimensional model. Finally, based on the principles of economy, environment and equity, the equal proportion allocation method was adopted to initially allocate the water environment capacity of each administrative unit. GDP, regional area and population were selected as the distribution indicators of Gini coefficient, and the distribution schemes were evaluated and optimized by using the Gini coefficient under each indicator. The results show that the water quality of Chengde section of Luanhe River is better, and the water environmental capacities of COD, ammonia nitrogen and total phosphorus are 5 203. 61 t/a, 505. 71 t/a and 72. 92 t/a, respectively. In the allocation of environmental capacity, the four allocation schemes meet the requirements of relative fairness, and the scheme with large weight of environmental benefits is more reasonable than other schemes.