The utility model relates to the field of gas decomposition product detection, and in particular relates to an SF6 gas decomposition product detection device based on a photoacoustic spectrometry technology. The detection device comprises a shell, wherein a singlechip and an accessory circuit are arranged in the shell; the singlechip and the accessory circuit are connected to a power source; the singlechip is connected to an infrared light source through a power switch tube; the infrared light source is opposite to a light source incidence opening of a photoacoustic cell; a resonant cavity is arranged in the photoacoustic cell; round holes communicated with the resonant cavity are formed in two sides of the photoacoustic cell; microphones are arranged in the round holes in two sides and are connected to the singlechip through a lock-in amplifying circuit; the singlechip is connected to a display screen; a gas inlet and a gas outlet communicated with the resonant cavity are formed in the upper end of the photoacoustic cell. The detection device disclosed by the utility model avoids the problems of cross interference and electrode poisoning caused by an electrochemical method, system noises are lowered and the detection accuracy is improved; the detection device is simple and compact in structure, small in volume and good in stability.