The invention discloses a carbon dioxide concentration-corrected exhaled gas multi-component detection instrument and detection method. The detection instrument comprises a filter flask, a carrier gas pump, a drying pipe, a sampling gas pump, a sample ring, a first two-phase three-way solenoid valve, a second two-phase three-way solenoid valve, a third two-phase three-way solenoid valve, a chromatographic column and a detection gas chamber, and after communication, a sampling passage, a washing passage and a detection passage are respectively formed. The detection gas chamber is of a cuboid structure and is provided with a PCB tank, a MOS tank, a carbon dioxide sensor tank, a temperature measuring hole, a gas reaction chamber and the like. A sensor can quickly give a response and restore a baseline; after the outputted response is subjected to signal processing and calculation, hydrogen and methane concentrations are obtained and can be corrected according to carbon dioxide concentration, so that sample acquisition constraints are reduced, and the error caused by breath collection and other human factors is reduced. The carbon dioxide concentration-corrected exhaled gas multi-component detection instrument is perfect in functions, small in size, simple and convenient to operate, higher in accuracy, stability and repeatability and friendly in user interaction, and facilitates popularization of large-scale clinical application.