The invention discloses a signal processing method and a signal processing device. The signal processing method comprises the following steps: acquiring a pre-distortion signal for counteracting nonlinear distortion generated by a sending passage; superposing the pre-distortion signal to the sending passage so as to counteract the nonlinear distortion; outputting a nonlinear distortion counteracted signal through the sending passage. Through the mode, the nonlinear distortion of the sending passage can be removed without the change of an existing sending passage, so that the sending performance of a transmitter is improved. The signal processing method and the signal processing device are simple and easy to implement.