The present invention discloses a method and a system for out-of-band predistortion linearization, comprising steps of: dividing base band inputted or intermediate frequency signal into an in-band signal branch and an out-of-band signal branch; processing the in-band signal to form RF (Radio Frequency) signal; processing the out-of-band signal to form out-of-band predistortion signal for pre-compensating the in-band signal; adding the in-band signal with the out-of-band predistortion signal, and taking the result as the input of RF power amplifier. The present invention compensates the nonlinear distortion of the RF power amplifier by a way of out-of-band compensating signal in a wireless communication environment, thereby avoiding the limitation of improving performance of conventional predistortion method, and solving the limitation of bandwidth and capability of the predistortion system caused by memory effect.