In order to reduce the influence of communication information on integrated waveform ambiguity function,it proposes an integrated signal model of radar communication based on spread spectrum modulation with multiple OFDM symbols and analyze it from the angle of waveform and radar ambiguity function respectively. By using the method of OFDM modulation in pre spread spectrum of communication information, the performance of ambiguity function of integrated signal can be significantly improved, and the range sidelobe can be reduced.Theoretical analysis shows that the range sidelobe of the integrated signal is determined by the autocorrelation, cross-correlation characteristics of the pseudo-random coded sequence and modulation communication information , which provides guidance for the performance improvement of the waveform. The simulation results show that the influence of different values of the spreading factor, the number of subcarriers, the length of the data on the radar communication integration signal range ambiguity function sidelobes, and provide the basis for the performance optimization of integrated signal. The design of radar integrated signal model can effectively improve the sensitivity of communication information and Doppler frequency shift to meet the radar detection waveform requirements.