Abstract:As an important safety protective valve in vehicle fuel system, rollover valve has a lot of testing items, and most of them require high accuracy. Those main items test exhaust or inspiratory air flow rate under various angle attitude and positivenegative pressure. An airsealing testing system was designed for rollover valve based on S7200 smart PLC, by which clamping, plugging and airsealing testing etc could be achieved. Practice has proved that it can meet testing requirements and improve testing efficiency.