The detection of dissolved gases in online oil is one of the important items in the state evaluation of high-pressure oil-immersed power transformers. Compared with the gas chromatographic analysis and physical chemical sensing methods of dissolved gases in oil. The future application prospects are industrial. The world and the academic community are optimistic. Aiming at the shortcomings of traditional transformer oil chromatographic analysis, such as large error, complicated operation procedure and long detection period. This paper mainly applied new technologies to the field, developing a new remote online analysis system for dissolved gas spectrum in transformer oil. The system adopts distributed topology structure, firstly analyzes the on-site monitoring layer. Three levels of functional modules, substation layer and remote monitoring layer, developed a complete set of real-time acquisition monitoring and analysis software, and successfully applied to a 220kV transformer in a city, compared with the historical detection data to verify the system"s Effectiveness and stability.