Currently, China's power demand continues to grow steadily, and the characteristics of peak load are becoming more prominent. With the rapid development of new energy generation technologies, the regulation and support capabilities of the power system face many constraints. In order to improve the accuracy of frequency control in the power system and maintain reliable and stable frequency characteristics, this paper focuses on the application of Active Disturbance Rejection Control (ADRC) in the Load Frequency Control (LFC) system of multi-area interconnected power load. A Firefly Algorithm Sparrow Search Algorithm (FASSA) is proposed to enhance the optimization accuracy and stability of the algorithm, and optimize the self-disturbance rejection control parameters designed for better dynamic response performance of the system. In addition, simulation comparisons are conducted on the established multi-area power system under different control modes. The results show that the proposed algorithm exhibits better search performance, robustness, and smaller deviation compared to the original algorithm, and the designed controller possesses excellent control properties, demonstrating superior practical application value.