Abstract: In the process control of modern technics，the industry requires visualization，intellectualization and networking of the process，so that it can timely analyse and judge the running status of the equipment in accordance with the real-time running parameters. The author analyzed the typical failure of ion nitriding furnace，via both hardware and software to implement the ion nitriding furnace fault diagnosis system. The condition monitoring and fault diagnosis system of ion nitriding furnace was constructed with QTouch configuration technology，programmable controller technology and sensor technology. The experimental results showed that the system could detect the state of the entire nitriding process system，completed the system fault information diagnosi，alarm，prompt and other functions.

Key words: ion nitriding furnace, fault diagnosis, PLC, QTouch