Abstract: The motor’s tail gas must be handled by trinity catalyst before it exhausts and the rate of purification is related to the content of the oxygen. At the same time, matching to the economization, we can realize the real time control of the proportion of air and fuel by mensurating the content of oxygen, and insure that the fuel in cylinder burns well. In this way, the harmful gas is reduced, so the oxygen gas sensor is needed. This paper described the development condition on ZrO2 gas sensors, and introduced the sensor’s structure, working principle and applications. Key technology, such as new extender’s appending are also discussed.