In order to make the model-free adaptive control（MFAC） better solve the control problem with noisy system, this paper examines the noise system and applies improved tracking differentiator in MFAC. Filtering is performed in the feedback process, and a MFAC method based on improved tracking differentiator（ITD） is proposed. The convergence of the algorithm is also proved. The simulation experiment proves that the improved control method can quickly track a given signal and has good resistance to noise interference. Finally, it is applied to the control of the drum water level of circulating fluidized bed （CFB） boiler.