The utility model discloses an online chromatograph carrier gas collecting device for directly collecting gas from air. The device comprises a gas filtering module, an air compressor, a gas drying module, a gas storage module, a control module and a reproduction module. The device provided by the utility model has the advantages that in-situ air is adopted to produce the carrier gas required by the transformer online chromatograph system so as to solve the problem of inconvenience of the transformer online chromatograph system due to regular replace of carrier gas cylinders.