Abstract: In the conventional radar system, the transmitted waveforms in different pulses are same, whereas it transmits different integrated orthogonal frequency division multiplexing (OFDM) waveforms in the integrated radar and communication system to maximize the communication data rate. The diversities in different pulses may result in the performance degeneration of the energy integration of target. For this problem, the derived results in theory enable us to conclude that the variation of phase in the main lobe has a linear relation with time delay after the pulse compression is performed, if the phases of communication modulation information are with uniform distribution. Moreover, among different pulses, compared with the variation of phase caused by unmatched filtering, the variation of phase due to Doppler is dominant. Theoretical analysis and simulation results show that the coherent integration of target energy in the main lob is unable to be influenced by the integrated radar and communication waveform based on OFDM.