A method, receiver, transmitter and communication system for suppressing Out-of-Band (OOB) Radiation are provided by the embodiments of the present invention, which effectively restrain the OOB Radiation of Orthogonal Frequency Division Multiplexing (OFDM) signals with lower complex level arithmetic. The method includes the following steps: for each user Uk of OFDM system separately generating a precoding matrix Gk of data of said user Uk; precoding data of said user Uk by using said precoding matrix Gk; mapping said precoded data of all users to corresponding sub-carriers, and implementing OFDM modulation to form transmitting signals. The method provided by the present invention reduces the complex level of precoding matrix selection for the transmitter; and greatly reduces the computing complex level of the receiver, because for the receiver, it only needs to de-precode the data of user Uk, and does not need to de-precode it together with the data of other users on all sub-carriers when receiving the transmitting symbols corresponding to the data of user Uk coded and transmitted by the transmitter.