Inter-carrier interference (ICI) due to Doppler spread is analyzed for OFDM system in highly mobile applications, and then an iterative ICI mitigation method is developed. With the Jakes' model for the Doppler power spectrum and linear model in one OFDM symbol interval for time-varying channel, the analytical closed-form expression of Signal-to-interference ratio (SIR) and Signal-to-interference-plus-noise ratio (SINR) are de- veloped with neither assumption on the statistical charac- teristic of ICI nor constraint on the statistical model for the fading channels. Then, a joint detection algorithm is proposed to iteratively mitigate ICI and estimate channel and detect symbols, where the ICI from a few neighbor- ing interfering subcarriers which contribute the majority of ICI power is regenerates and partially subtracted from the received signal in order to mitigate decision error accu- mulation. The number of concerned interfering subcarriers and the optimal partial ICI cancellation factor are inves- tigated for the tradeo® of complexity reduction and Mean square error (MSE) minimization. Simulation results ver- ify the proposed method can mitigate ICI e®ectively.