Abstract: In order to solve the problems that adaptive notch filter(ANF) based frequency estimation method is complex, biased, and unstable under noise condition, a new ANF based unbiased frequency estimation method is proposed. Firstly, based on simple structure of FIR adaptive notch filter, the iterative recursive formula of frequency estimation is proposed to improve the convergence performance after the analysis of error function performance; Secondly, the bias analysis of the iterative recurrence formula of frequency estimation is carried out to confirm the deviation compensation item, which should be useful for obtaining unbiased frequency estimation results. Finally, the proposed method is calculated and analyzed to verify the effectiveness of the proposed FIR frequency estimation method in terms of convergence, anti-noise performance and unbiasedness.