As a kind of stable

safe

and environmentally friendly electronegative gas

CF

3

I has received much attention in the field of substitute gases research in recent years

while the decomposition components forming mechanism of CF

3

I with micro-aerobic under discharge is seldomly studied.Consequently

we firstly explored the energy of decomposition components generated by the reaction between free radicals such as CF

3

· and CF

2

:based on the density functional theory（DFT）

and calculated the energy change of the reaction path by using the transition state theory.Then

we obtained the reaction heat and activation energy of the components.Secondly

the main reactions and products of CF

3

I under discharge with micro-aerobic environment were analyzed.Finally

based on Fourier transform infrared absorption spectrometry（FTIR）

the discharge decomposition components of pure CF

3

I and CF

3

I/O

2

mixture were experimentally verified.The results show that there is no energy barrier in the process of generating CF

4

C

2

F

6

C

2

F

4

and C

2

F

5

I

while the generation of C

3

F

6

and C

3

F

8

requires a certain activation energy.Free radicals and molecular produced by the decomposition of CF

3

I and O

2

can generate COF2 through three reaction paths.The experimental results show that the existence of O

2

can promote the consumption of CF

3

I and destroy the self-recovery process of the insulation

so that the dielectric strength is deteriorated.The insulation performance of CF

3

I under high pressure is better than that of low pressure

which is more reliable.