Abstract: A method for realizing predistortion compensation processing for 5G NR in-band modulated signals includes configuring the modulator to output a continuous wave signal, switch the output frequency interval of the signal to be consistent with the 5G NR subcarrier bandwidth, and record the power value P0 corresponding to the current frequency through the power meter. The power measurement difference between all points and P0 is calculated and performs normalization, and generates a compensated channel impulse response after shaping filtering; converts it into a power compensation factor in the time domain; performs inverse Fourier transform to generate I and Q baseband signals; generates compensated baseband data; the generated baseband data is filtered, and an analog zero intermediate frequency signal is generated, which is input to the broadband demodulator for frequency conversion modulation of the 5G NR broadband signal. The method operates without the need to modify the device circuit in the channel.