Formed by overcoming the drawbacks of the classic proportional-integral-derivative（PID） control， the active disturbance rejection controller（ADRC） is a new-type controller independent of the system model and characterized by good performance and simple algorithm. In light of the large delay， strong inertia， and uncertainty of the superheated steam temperature process， in order to improve the dynamic performance and robustness of the control system， an active disturbance rejection control scheme is presented. The strategy does not have to have an accurate knowledge of the model parameters to realize disturbance compensation. Building the blocking controller on STAR-90 with the modules of the system is of great significance for engineering application. With the main steam temperature of a certain supercritical once-through 600 MW boiler as the object， tests under variable load conditions， 10% disturbance and the runback test have been conducted. The test results show that， compared with the PID control system， the main steam temperature control system with ADRC can ensure very good robustness and adaptability under modeling uncertainty and external disturbance while producing better dynamic performance than classic PID controller in the operation conditions.