SF6 in gas insulation systems may breakdown under high voltage, which can cause electrical system failure. An on-line gas detection and analysis system was developed for SF6 quality monitoring in gas insulation equipment. The basic components were introduced from the aspects of function modules, software/hardware development, as well as the final system integration. In order to validate the system feasibility, both laboratory and field tests were performed. Test results suggested that the system can improve the detection efficiency, and can make working environment safer for testers, which was important for the safety of electrical equipment.