Radar communication integration is a system with the function of target detection and information transmission, which is an important development direction in recent years. The spectrum efficiency of integrated system has been the focus of research. This paper designs a radar communication integrated signal based on 64QAM-LFM, and makes theoretical and simulation analysis from the aspects of communication performance and radar performance. The results show that 64QAM-LFM signal is a radar communication integrated signal with large spectrum efficiency, high range resolution and velocity resolution.