Abstract: Device-to-device (D2D) communication technology improves spectrum utilization by multiplexing spectrum resources of cellular systems, but the introduction of D2D will cause interference to cellular systems. How to properly select the D2D / cellular communication mode and perform power optimization control has become the key to reducing interference between D2D and cellular systems and improving network performance. This article considers the scenario of D2D user multiplexing cellular uplink, and proposes a communication mode selection scheme based on distance and joint power control. In this solution, the ratio of the distance between the D2D user and the cellular user to the base station determines whether the D2D user uses the Underlay mode to communicate, and then the combined power of the D2D link and the cellular link is achieved under the constraint of the transmit power of the cellular user and the D2D user Control, and finally derive the optimal user power allocation scheme that can maximize the total system throughput. According to the simulation results, the joint power control scheme proposed in this paper can effectively improve the overall throughput of D2D and cellular systems while reducing the interference between systems, thereby improving the performance of the system.