Abstract:The water island system of Thermal power generating unit including raw water pretreatment, circulating cooling water, boiler supply water and drainage is very important for of the safety, environmental protection and stability of power generation. The control system of water island is complex and isolated,so that the overall situation of water island is difficult to establish for monitoring, calculation and analysis. According to the water resources management, environmental protection and the requirement of energy saving , water saving, lean management and economic performance, an operation optimization system to monitor and optimize the operation of water Island must be created. The paper will introduce an operation optimization system of water island through the power generation big data platform. The production data of power plant production are collected and stored by using real-time and relational database such as AIRDB, MARIADB and NOSQL. Using machine learning, AI and data analysis to support remote monitoring, real-time analysis and smart alarm of water island. system. The user of water island can get Operational guidance through the system. At present, the system has been applied in a power plants and has played an important role in energy saving and operation management of power plants.