With the continuous penetration of renewable energies,thermal power plants are facing more frequent and wider variable load operation. The control of high order,large inertia superheated steam temperature processes in power plants is facing a great challenge. Therefore,a phase compensation based active disturbance rejection control (PC-ADRC) strategy for a class of high-order,large-inertia processes is proposed. Firstly,the working principles and control problems of SST system are illustrated. Then,the phase compensation (PC) network model is derived carefully by low-frequency approximation. A model simplification method is presented,in which the PC is adopted to compensate process dynamics and obtain reduced-order plant equivalently. To facilitate engineering applications,its simple implementation and equivalent model analysis for the PC-ADRC system are also given. At last,the stability and robustness of the PC-ADRC control system are theoretically studied. Theoretical analysis and simulation results show that the proposed controller can effectively improve the robustness and fast response ability of the high-order process control system.