With the development of science and technology and the development of social economy, high-rise buildings have become the symbol of modern cities. As a kind of vertical transportation, elevators can carry a large number of people and goods, which plays an important role in buildings. The elevator is controlled by a programmable controller. Through reasonable selection and design, the control level of elevator can be effectively improved, and the control effect of elevator can be achieved. The ladder diagram control system based on Siemens s7-200plc is designed. On the basis of introducing elevator structure, control requirements of three-story elevator and how to realize the design of control system and PLC in elevator control system, ladder diagram, program debugging and experimental device, the model of elevator module QSPLC-III is analyzed. The simulation experiment is carried out in the elevator control system.