In this paper,a robust adaptive Kalman algorithm for a second-order infinite impulse response (IIR) notch filter to detect the frequency of sinusoid signal in the white gaussian noise is proposed. Firstly, a general expression for the steady-state sinusoid frequency estimation based on minimum mean square error (MMSE) criterion in terms of state-space equations is derived. Secondly, a robust adaptive Kalman algorithm for the state-space equations with unknown noise statistics is given. Finally, computer simulation results are presented to confirm the effectiveness of the proposed algorithm.