The steam generator of nuclear power plant is a nonlinear,time-varying system.Application of the active disturbance rejection control method in the water level control of steam generator can solve the contradiction between speed and overshoot in the conventional PID control system,and it also can compensate the internal and external disturbances of the object model dynamically.However,ADRC parameters are numerous and without uniform adjustment specification,and are very difficult to be tuned.In order to over-come the difficulties in the parameter tuning of the ADRC,the adaptive genetic algorithm is used to tune ADRC parameters.The simulation results show that its robustness and its control quality are better than those of the traditional cascade PID control.