The present invention relates to a method for suppressing inter-carrier interference in an orthogonal frequency division multiplexing mobile communication system, comprising: performing down conversion of the signal received in the receiver; removing the cyclic prefix of the signal so as to obtain the original signal; performing cyclic extension of the original signal over again; adding a window to the signal after cyclic extension, wherein the window function satisfies Nyquist criterion. The method according to the invention does not need time delay information of channels, and thereby is simple to realize. The selected roll-off coefficient can be up to 1 so as to suppress ICI to the utmost extent. Additionally, the invention also suggests that the generic window functions without the ICI can be used in OFDM system, which makes the system capability of suppressing ICI stronger by means of finding the best polynomial coefficients on the condition that the roll-off coefficient is 1.