To achieve efficiency optimization the working frequency of a wireless power transmission system should be slightly higher than the resonant frequency to realize zero voltage soft switching (ZVS). With underwater environments, the misalignment between the receiving side magnetic coupler and the transmitter side magnetic coupler will be generated, thus the resonant frequency will change. Traditional frequency tracking method determines the frequency status by detecting phase angle, zero crossing, and so on, however, these methods are susceptible to interference. In this paper, a simple frequency tracking method with high accuracy of frequency status detection is proposed. With this method, the frequency status can be detected by the direction of current flow during the dead zone, thus the frequency status can be detected with high accuracy. The frequency status detection method and tracking method are analyzed in detail and the correctness of the proposed methods are verified by simulation results.