The invention provides a closed-loop degaussing method based on a stress monitoring system. The method comprises a step of determining the positions of sensors for measuring the hull stress in the stress monitoring system and then obtaining relationships between a hull stress change and a fixed magnetic field and an induced magnetic field at these installation positions based on a simulation calculation method and/or an experimental method, a step of obtaining relationships between the fixed magnetic field and the induced magnetic field at these installation positions and magnetic characteristics at a specified distance outside a hull through simulation calculation and/or experiment, and a step of connecting a closed-loop degaussing system and the stress monitoring system to a network to get real-time hull magnetic features. According to the method, a magnetic sensor is not needed or a small amount of magnetic sensors are used in cooperation, the measurement resources of the stress monitoring system is fully used to obtain the high-precision magnetic characteristics, and the closed-loop degaussing control effect is improved.