Aiming at the problem of poor control effect of active disturbance rejection control (ADRC) for thermal system with high order and large inertia characteristics, a design method of ADRC based on high-order system model information compensation is proposed. Based on the theoretical analysis, the physical significance of each parameter and the quantitative parameter tuning method are given, and the reason why the proposed ADRC 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 result of the comparative simulation and robustness test show that the proposed method has better control effect than PI/PID in set point tracking, disturbance rejection ability and performance robustness, and it can also significantly improve the control effect of low-order ADRC on high-order large inertia process, which has good engineering promotion potential.