Abstract: ‍ ‍In order to realize the multifunctional integration of electronic devices that develop separately， the integration of radar communication has become a hot spot in the field of integration research. Space-frequency modulation （SFM） is a modulation technology that can map one-dimensional communication data to two dimensions： space and frequency. When space-frequency modulation technology is applied to radar communication integrated waveform design， it can obtain space-frequency modulation common waveform， which can realize radar detection and communication transmission functions at the same time， in addition， it can not only obtain the radar detection performance improvement brought by the scale gain of array antennas， but also obtain the improvement of the communication data rate after the use of airspace information for communication data modulation. In this paper， the design process of radar communication integrated common waveform based on space-frequency modulation was first introduced， which introduced that the integrated transmission signal is generated by space-frequency modulation and the transmission beamforming is realized by combining the array model. And then， aiming at the demodulation process of integrated signal， a sequence-based subarray element estimation optimization algorithm was proposed. Theoretical analysis showed that the larger the scale of the subarray is， the more susceptible to the influence of noise can it be. On the basis of this conclusion， by modifying the maximum subarray estimation value， the total estimated number of elements can be guaranteed to be consistent with the reality， thereby effectively reducing the bit error rate. Finally， aiming at the problem that the current radar communication integrated waveform performance analysis based on space-frequency modulation is not comprehensive enough， the communication performance and detection performance boundary of radar communication integrated common waveform based on space-frequency modulation was analyzed， so as to provide a basis for this radar communication integrated waveform to apply to different scenarios based on the detection and communication performance trade-offs. The simulation results showed that the bit error correction scheme proposed in this paper can effectively reduce the bit error rate， and by adjusting the key parameters of the integrated waveform， the best compromise between radar and communication performance in different scenarios can be achieved.