Based on the characteristics of highway tunnel, the design of tunnel ventilation system was proposed. The system combined PLC with the frequency converter and touch screen. Using the sensor in the realtime detection of traffic environment, through the PLC controlling frequency converter to drive tunnel fan, the air indicators conformed to the safety standards and at the same time saved energy. The introduction of touch screen could realize realtime automatic monitoring of the whole system. At last, the whole simulation and debugging of the control system was realized by computer simulation technology. Experiments proved that the system ran smoothly and had reliable performance, friendly manmachine interface, high level of automation, and the good market prospect and application value.