Abstract: Multi-motors linkage control system has been widely used in modern industry. Based on the existing network control platform of the laboratory, an all-digital electrical interlocking control system constructed by Profibus-DP field bus is designed in this paper. Firstly, the system uses Siemens MM440 inverter with Pofibus bus interface as the signal conversion device between PLC and three-phase asynchronous motor. Then, an improved proportion integral separation PI control algorithm is used to realize system control. Finally, the system is completed. The speed-up and smooth control of the three-phase asynchronous motor and the real-time monitoring of the lower-machine linkage control system by the WinCC monitoring software of the upper computer achieve the requirements of the positive dodecagon approximation. The experimental results show that this system has the characteristics of low-cost, rapid response and high control precision.