In order to realize on-line quantitative detection on SF_6 and effective control of running state of SF_6high voltage power supply system,a concentrated SF_6 quantitative ultrasonic on-line detection system hasbeen developed based on the actual demand of electric power system consumers.There are four majorcharacteristics in this system.Firstly,the gas of maximum 64 detection points is transferred through thespecific air path to the detection devices to be detected and analyzed,thereby the electrical lines and thecomplicated installation of the collectors can be avoided;secondly,the differential technique is used toshield the influence of environmental factors,which effectively improves the accuracy of the acoustic detection ;thirdly,the SF_6 concentration is determined by the speed and phase in the ultrasonic wave transmissionprocess,therefore there is no secondary pollution for the purely physical means;finally,the matureembedded technique is applied in this system to improve its intelligence and stability. In order to realize on-line quantitative detection on SF_6 and effective control of running state of SF_6high voltage power supply system, a concentrated SF_6 quantitative ultrasonic on-line detection system has been developed on the actual demand of electric power system users. Here are four majorcharacteristics in this system. Firstly, the gas of maximum 64 detection points is transmitted through thespecific air path to the detection devices to be detected and analyzed, thereby the electrical lines and thecomplicated installation of the collectors can be avoided; secondly, the differential technique is used toshield the influence of environmental factors, which effectively improves the accuracy of the acoustic detection; thirdly, the SF_6 concentration is determined by the speed and phase in the ultrasonic wave transmissionprocess, there there no no secondary pollution for the purely physical means; finally, the matureembedded technique is applied in this system to improve its inte lligence and stability.