Poor control of the steam generator water level is the main cause of unplanned reactor shutdowns in nuclear power plants. Particularly, at low power levels, it is a difficult task to control the water level due to the shrink and swell phenomena and the unreliable flow measurements. In this paper, a model free adaptive control (MFAC) strategy is proposed, in which the MFAC is used in the primary control loop and the PID controller is adopted in the secondary loop. The simulation results show that, compared with the cascade PID control, the proposed control method has better stability, adaptability, and robustness. Moreover, it is suitable for industrial applications due to its simple structure and easy implement.