This design is lift control system's PLC controls four elevators. In the design process, must first come up the idea system from the whole to divide into the hardware design and the software design approximately. The 1st chapter introduced elevator's design requirements; The 2nd chapter introduced elevator's basic structure; The 3rd chapter detailed introduction each controlling unit. Mainly introduced 2 bulks in the 3rd chapter: (1) the sedan theater box instruction and the hall incur trade the electric circuit; (2) refers to the level electric circuit and the orientation control electric circuit. The 4th chapter introduced the flow chart; The 5th chapter carried on the system design, before the design, introduced the programmable controller, then carried on PLC the input/output address assignment, then used the trapezoidal chart to carry on the procedure the compilation. The 6th chapter introduced hardware's design; The 7th chapter for software and hardware debugging process; The 8th chapter introduced carries on the simulation, the monitoring movement using the configuration software.