Abstract: This article primarily introduces the construction and application of the marine online monitoring buoy system in Zhejiang Province. The system composed of four parts:marine buoys, monitoring platform, information management and operational maintenance. The stable operation of this system which had been running for more than three years indicates the feasibility and validity of using buoys on marine real-time monitoring. Data collected from marine buoys are applied in developing information products such as environmental report in coastal tourism region and short-term warning report of red tide. Finally, prospects are suggested in relation to the sensor technology, data quality control and data applications.