Because GC has advantages of high separation efficiency, fast analysis, less samples and being used for the multi-component measurement etc, it is widely used to analyze raw materials and control of products in industrial production .The personnel quality, the nature of the samples, the selection methods and the instrument itself and other reasons caused some faults which interfered the normal analysis seriously,so it was very important to master the usage of the GC ,to master accurate methods of removing instrument faults.Based on usable method of Agilent 4890D GC， the faults were analyzed and the troubleshooting methods of GC were introduced.