Abstract: ‍ ‍The continuous development and popularization of 5G technology have led to an increase in the demand for wireless devices for spectrum resources， and the problem of tight spectrum resources has become increasingly prominent. To improve spectrum utilization and effectively address the challenge of limited spectrum resources， integrated sensing and communication （ISAC） technology has emerged. In ISAC systems， the communication and sensing modules share the same waveform and hardware platform， thus improving spectrum and equipment utilization. Among these， the ISAC system based on orthogonal chirp-division multiplexing （OCDM） has superior anti-jamming performance against Doppler shift and outperforms the traditional system. However， the peak-to-average power ratio （PAPR） of the OCDM signal is high because of the need to convert from the chirp domain to the time domain using the inverse discrete Fresnel transform， and the high PAPR tends to cause nonlinear distortion， affecting the performance of ISAC systems. To address this issue， a PAPR suppression method based on the chirp preservation method was proposed for OCDM pass-sense integrated signals by dividing the entire chirp of the OCDM signals into two parts. One part was used to transmit signals that reduced the overall PAPR， and the other part transmitted the communication data normally. These parts are termed the optimization and communication subcarriers， respectively. The PAPR of the integrated signal was related to its non-periodic autocorrelation function， and the resulting signal on the optimization subcarrier was optimized using the Gerchberg-Saxton algorithm to reduce the overall PAPR of the signal. All subcarriers were used for radar signal processing to ensure sensing performance. Simulation results showed that the PAPR of the integrated signal could be reduced by approximately 2 dB and 3 dB when 10% and 25% of the subcarriers were used for optimizing the signal PAPR， respectively， and the value of the complementary cumulative distribution function is 10^-2.