The development of automatic core filling rate monitoring system is to fill the shortage of core condition monitoring in the process of core extraction. The core filling rate automatic monitoring system is composed of main controller, reserved temperature and pressure monitoring module, Hall sensor module, data storage module and serial debugging module. The principle of core status monitoring is based on Hall effect. The coring speed range of the system can be monitored is 0-30mm/s, and the monitoring accuracy is about 1%. The system uses low-power AVR single-chip microcomputer, large-capacity memory, high-speed USB interface and other devices or modules, and has the functions of online debugging, programming and upgrading. The experimental results show that the system can automatically monitor the process of core penetration into the core tube at a water depth of 3000m (0~35MPa hole bottom pressure), which can provide theoretical guidance for the selection of field sampler type and the optimization of working parameters of the sampler, and has a broad application prospect.