Abstract: An on-line multi-component gas analysis system based on a spectral absorption technology includes a housing, wherein the housing includes an air inlet hole and an air outlet hole which are respectively connected with an air inlet pipe and an air outlet pipe, and the housing includes a dust removal and dehumidification device, a micro vacuum pump, an electronic flowmeter, and a plurality of different gas sensors; the dust removal and dehumidification device, which is configured to perform dust removal and dehumidification treatment on a gas entering from the air inlet hole; the micro vacuum pump, one end of which being connected with the dust removal and dehumidification device through a pipeline, and the other end of which being connected with the electronic flowmeter; and the plurality of different gas sensors. The disclosure includes an analysis method based on the on-line multi-component gas analysis system based on a spectral absorption technology.