In order to ensure the safety of underwater operation, it’s important to monitor the physiological signals of underwater operators in real time. In this article, we have introduced a real-time physiological signals monitoring system of underwater operation. The proposed system consist of three key modules: (1) the photoelectric sensors were used to collect physiological signals to effectively reduce the influence of water on physiological signal data collection, (2) the data were transmitted wirelessly through underwater acoustic communication technology, which can improve the freedom of underwater operators, (3) the physiological, psychological and early warning analysis parts were integrated on the deck unit. By combining the uploaded physiological information data with historical data for statistical analysis and comparison, higher-level early warning information or alarm information can be decided in real-time. The prototype has been developed and experimented underwater, feasibility and reliability of key modules have been verified.