Aiming at the problem of poor control effect of standard ADRC for thermal system with high order and large inertia characteristics, a design method of compensation ADRC based on high order system model is proposed.SBased on the theoretical analysis, the quantitative parameter tuning method and the physical significance of each parameter are given, and the reason why the extended state observer can improve the control effect compared with the standard ADRC controller is analyzed from the perspective of observation error, open-loop frequency characteristic and stable region. The simulation results show that the proposed method has a good improvement effect on set point tracking, disturbance rejection ability and performance robustness. The proposed method can significantly improve the control effect of large inertia process, and has a good engineering promotion potential.