Abstract: Fusion of radar and communication (RadCom) is regarded as an important research direction of the next generation of communication technology, which has attracted extensive attention from academia and industry. In this paper, a multiuser orthogonal frequency division multiplexing (OFDM) RadCom scheme based on frequency division multiple access (FDMA) is studied. The key problem lies in the multiuser subcarrier allocation. Different subcarrier allocation methods will lead to different sidelobe levels in range processing, which will affect the ranging performance of radar; when subcarriers are continuously assigned and randomly assigned, there will be obvious sidelobe in range processing of each user, and the performance of radar ranging will be degraded seriously. In order to find a proper subcarrier allocation method that makes the sidelobe level of radar range processing of each user as low as possible, we take the integrated sidelobe level in the range observation window as a cost function. We find that when the number of users is limited and the subcarriers are allocated with equal intervals, the cost function achieves the minimum value, and the sidelobe level of all users is the lowest in the range observation window, so all users can effectively realize the radar detection function. Finally, in the internet of vehicles (IoV) scenario, different subcarrier allocation methods are simulated and compared to verify the effectiveness of the equal interval subcarrier allocation method.