Abstract: To analyze the variable load dynamic characteristics and optimal control strategy of the 100 MW cascade supercritical carbon dioxide (S-CO₂) cycle, the dynamic simulation model of the 100 MW cascade S-CO₂ cycle is established by using the multi-disciplinary simulation platform (MSP). Considering the lower cost and rapidity of valve regulation, four load control strategies were proposed (high-temperature turbine throttling regulation, low-temperature turbine throttling regulation, high-temperature turbine bypass regulation, and low-temperature turbine bypass regulation), and the changes of key parameters in the process of load raising and lowering of the system were analyzed. The results show that different load control strategies had little influence on the compressor power. The use of high-temperature turbine throttling regulation has the highest cycle efficiency, and the cycle efficiency is 27.60% and 21.22% when the load rate is 75% and 50%, respectively. The throttling regulation will cause the maximum pressure to increase, and the maximum pressure with high-temperature turbine throttling regulation is 28.57 MPa when the load rate is 50%. The risk of overpressure can be avoided by bypass adjustment, but the cycle efficiency is low. On the premise of ensuring the pressure-bearing capacity of the system, it is recommended to use the high-temperature turbine throttling adjustment method to adjust the load.