The paper focuses on how to rationally distribute the load of cascade hydropower station in the short term economic operation to meet the grid requirements and improve the water energy efficiency of cascade hydropower stations. In this paper, a calculation method of energy storage for cascade hydropower station is presented, the change of cascade storage caused by power generation of different hydropower stations is studied, and the influence of reservoir capacity characteristics on load distribution of cascade hydropower stations is analyzed. According to the short term economic operation and dispatching requirements of cascade hydropower station, the load distribution model of cascade hydropower station based on the maximum storage capacity at the end of the term is constructed. Taking the short-term load distribution of cascade hydropower stations in the Nam Ou River Basin of Laos as an example, four scheduling schemes with different boundary conditions are calculated. The results show that the load distribution results of cascade hydropower stations in the Nam Ou River based on the maximum energy storage the end of the period are as follows: Nam Ou4 and Nam Ou1 in the downstream with larger changes in water level per unit storage capacity are preferentially stored, Nam Ou7, Nam Ou6 and Nam Ou2 in the upstream with larger storage capacity are preferentially supplied and generating power. The research results can provide guidance for the short-term economic operation and dispatch of cascade hydropower stations, and help to improve the water energy utilization efficiency of cascade hydropower stations.