Abstract: Conventional fast Time-Varying (TV) Channel Estimation (CE) methods for Orthogonal Frequency Division Multiplexing (OFDM) systems are performed in the time-domain, which need optimal even-pilots to track the time-domain channel impulse response (CIR) variations over one symbol period by Basis Expansion Model (BEM). And the multi-path channels are assumed sample spaced. The required sample spaced channels and even-pilots are not satisfied in practical OFDM systems. As a result, the CIR leakage occurs and the estimation errors increase greatly. In this paper, a frequency-domain fast TV CE method for practical OFDM systems is proposed. The frequency-domain transmission function is used for estimation, and finally the frequency-domain channel matrix is obtained. The proposed method is performed in the frequency-domain, so that it is immune to the time-domain CIR leakage. Simulation results demonstrate its validity in Symbol Error Rate (SER) and Mean Square Error (MSE).