Abstract: as the information feedback carrier of the running state and health state of the equipment, the on-line monitoring device of the insulating oil chromatography monitors the characteristic gas in the transformer oil from time to time, at present, the on-line monitoring device of insulating oil chromatogram usually uses the meteorological chromatogram method, this method needs to use the carrier gas, when the pressure of the carrier gas is insufficient, the on-line chromatogram can not run normally, the detecting device is unstable, the detecting data is inaccurate and even the device is damaged, in this paper, by developing a non-cylinder, maintenance-free carrier gas system to achieve the stability of carrier gas pressure and to eliminate the replacement of carrier gas cylinder equipment and security risks.