C4F7N/N2 decomposition product online detection device suitable for environment-friendly GIS

The invention discloses a C4F7N/N2 decomposition product on-line detection device suitable for an environment-friendly GIS. The C4F7N/N2 decomposition product on-line detection device comprises a first gas path unit, a decomposition product detection unit, a third gas path unit and a gas supply unit, the first gas path unit comprises a CO2 detection module and a H2O detection module which are connected, a gas inlet of the CO2 detection module is connected with a gas outlet of the GIS main gas chamber, and a gas outlet of the H2O detection module is connected with the decomposition product detection unit; one end of the third gas path unit is connected with the gas outlet of the detection unit, and the other end of the third gas path unit is connected with the gas inlet of the GIS main gas chamber; and infrared light emitted by a laser light source of the decomposition product detection unit is refracted for a plurality of times in the reflective gas chamber and enters the detector. The device can effectively