Abstract: In order to give full play to the efficiency of power generation and improve the utilization rate of water resources,the optimal operation of reservoir power generation is used as a hot research by experts and scholars. Luntan Key Water-Control Project,which gives consideration to the comprehensive benefits of flood control and power generation,is taken as an example. Based on building the both mathematical models of the medium-long term power generation and flood pre-release control,then a decision support system with fast online optimization is developed by using SOA architecture and J2 EE technology. The results show the system can improve the operation level of the reservoir power generation,and increase electricity generation about 12.3% during the hydrological year from March 2018 to February 2019. And the water abandonment rate of pre-discharge 12 hours in advance is effectively reduced by 21.42% compared with the actual water abandonment rate of dispatching in the actual flood from July 7 to 13,2019. The system realizes the scientific optimal operation,provides a scientific basis for the management decision,and creates more comprehensive benefits.