The greenhouse effect produced by SF

6

gas

which is widely used as insulating medium at present

is incontraction with the requirement of power system to the environmentally friendly

.Recently

C

4

F

7

N-CO

2

gas mix-ture

the environmentally friendly insulating medium

is considered to have a good engineering application pros-pect.Since the insulation performance of the gas mixture is closely related to the content of C

4

F

7

N and the gas pres-sure

the content of C

4

F

7

N gas mixture needs to be detected in the gas filling

exchange and maintenance in the ap-plication of future projects so to determine the actual concentration of the gas mixture.At present the related reportson the quantitative detection technology of C

4

F

7

N concentration in gas mixture is very rare.In this paper

the molec-ular configuration and spectrum optimization of C

4

F

7

N are performed based on the density functional theory and itsinfrared simulation diagram is obtained.Based on Fourier infrared spectroscopy（FITR）

the C

4

F

7

N/CO

2

gas mix-ture infrared detection platform is set up

the infrared absorption characteristic of C

4

F

7

N is analyzed with combina-tion of experiment and simulation.Moreover

the C

4

F

7

N characteristic infrared absorption band for concentration de-tection is determined in accordance with detection requirement at site

the quantitative detection of C

4

F

7

N in theconcentration range of 2%～10%is realized and the relative error of concentration detection does not exceed 5%.Thepeak is processed in accordance with Gaussian algorithm and the relative error of the concentration detection is re-duced to not more than 3%.The related research results provide important technical and theory reference for the rap-id detection of C

4

F

7

N in C

4

F

7

N/CO

2

gas mixture.