SF

6

/N

2

mixed gas as the substitute for SF

6

gas has been applied in many power devices. Detecting new generated decomposition gases such as COF

2

and N

2

O after failure of electrical equipment is useful to the fault diagnosis of electrical equipments. In order to study typical decomposition gases detection technology of SF

6

/N

2

mixed gas based on infrared absorption characteristics

the parameters of absorption line intensity and linear function given by HITRAN database for the above-mentioned typical components COF

2

and N

2

O are used. The infrared absorption spectrum

the central wavelength and the peak value of the absorption coefficient of COF

2

in the range of 400～2 000 cm

-1

and N

2

O in the range of 400～8 000 cm

-1

are obtained. At the same time

the effects of pressure and temperature on the absorption of COF

2

and N

2

O are analyzed. The results show that these two kinds of decomposition gases have strong absorption in the effective spectrum of infrared thermal radiation source in 1.2～10 μm

and can be detected by photoacoustic spectroscopy device based on infrared thermal radiation source. Meanwhile the absorption coefficient of the gas absorption line increases with the increase of pressure

but different gases increase in different degrees. As the temperature increases

the peak absorption coefficient of most absorption lines of the gas decreases

while a few absorption lines increase. The infrared absorption coefficient of COF

2

and N

2

O at operating conditions（pressure of 505 kPa

temperature 313 K） is greater than that at standard conditions（pressure 101 kPa

temperature 296 K）

and operating conditions are favourable for gas detection.