This paper introduced the improvement of the original control system of process control laboratory. The development of the liquid level, temperature and flow time-sharing control experiment platform adopting Profibus-DP fieldbus technology of Siemens. The newly designed control system using S7-300PLC as the master control unit, S7-224 as the slave control unit, PC and touch screen as the upper computer is able to achieve real-time monitoring on-the-spot operation, adjust control parameters, centralized management and provide convenience for experimenters. The practical operating results show that the platform not only extends the function of equipment and improves the utilization rate of equipment, but also help students understand and master the advanced control technologies, such as the technology application of PLC and touch screen, the process control engineering and the research of control algorithms.