Drifting buoys are monitoring devices for real-time collection of marine hydro-meteorological and ecological environment data. They are characterized by small size,low power consumption and easy deployment,and have played a significant role in marine observation. Based on the working principle of the drifting buoy,a new type of real-time monitoring system with automatic retransmission mechanism and the software implementation method are designed in this paper. The system uses the third-generation BeiDou communication method and has functions of instruction sending,data reception,storage,decoding,display,and automatic retransmission. It utilizes the flexibility of the queue to expand the retransmission range. Theoretical research and statistical analysis show that the new automatic retransmission mechanism can effectively improve the success rate of data recovery,and verify that the automatic retransmission mechanism in the real-time monitoring system has certain reliability and efficiency,providing reference for the subsequent design of real-time monitoring system in drifting buoys.