The thermal storage system is an essential part of the trough solar thermal power generation system. Due to the strong randomness, intermittency, and volatility of solar energy resources, to further improve the system's overall reliability to meet the needs of variable operating conditions, the paper optimizes the control strategy of the trough solar heat storage system. Taking the molten salt heat storage medium in the oil/salt heat exchanger, the core equipment of the heat storage system, as the critical research object, the article adopts proportional, integral, and differential (PID) control theories. It builds the system in the MATLAB/Simulink simulation environment mathematical model. We use the critical proportionality method to determine many critical parameters in the control system, tune the proportional coefficient, integral time, and other physical quantities in the PID controller, and analyze the proportional control, proportional-integral control, PID controls the respective dynamic response characteristics of these three different control systems. The simulation and comparative analysis results show that: compared with the other two control methods, PID control can effectively weaken the heat storage system oscillation caused by external disturbance, its dynamic response speed is faster, the adjustment time is shorter, and it can meet the requirements of operational stability. The paper adopts PID control, which reduces the control difficulty of the trough solar heat storage system and improves the adaptability to changes in external meteorological resources. The research results have particular guiding significance at the academic and engineering levels.