Abstract: The current compensation method of phase modem adopts the compensation method of combining phase and control frequency. When compensating linear frequency modulation（LFM） signal, the estimation value of frequency offset was large, which led to low fitting degree between the output response signal of the demodulator and given input signal. Based on this, a delay compensation method of LFM signal was proposed. The model of demodulator was established by calculating the signal sent by continuous phase modem, signal carrying phase and baseband signal; based on demodulator model, the linear frequency modulation signal and LFM delay signal were calculated, the frequency modulation slope of the signal was determined, the relationship between instantaneous frequency and time was determined, and the delay reason of LFM signal was analyzed; the total phase, receiving signal and frequency offset estimation value of demodulator were calculated, and the error of frequency offset estimation was controlled. When the estimated value of frequency offset was the lowest, the phase and frequency can be used to compensate the LFM frequency, and the delay compensation of the LFM signal of continuous phase modem can be completed. The experimental results show that in the pattern of phase compensation, frequency compensation and compensation combining phase with frequency, by using the new method proposed in this paper, the amplitude of the compensation signal is increased 1.6 V and 0.4 V, 0.8 V and 0.5 V, 3 V and 1 V, respectively, and the fitting degree of the demodulator output response signal is higher than the delay compensation method of synchronous signal circuit and compensation method based on CAN FD bus.