Abstract: Provided is a decision-making method and system for a suspension operation of a marine riser system based on a digital twin, which belongs to the technical field of marine oil and gas development. The decision-making method includes: acquiring original monitoring data by the sensor group to establish a physical entity structure model; acquiring real-time monitoring data to establish a digital twin model of the physical entity structure; and introducing navigation path and speed of the drilling platform, and a configuration and suspension mode of the riser system, combined with the digital twin model of the marine riser coupling system and a limit performance parameter, providing a suspension operation decision-making model of the riser system, and making a real-time accurate suspension operation decision based on a multi-objective optimization algorithm, so as to guarantee a safe and efficient suspension operation of the riser system.