C

3

F

7

CN/CO

2

is presently one of the most potential alternative gases to SF

6

while the study on degrada-tion characteristics of solid insulation after discharge at C

3

F

7

CN/epoxy resin（EP）interface is fairly rare

which is notconducive to evaluating the insulation condition of environment-friendly gas insulation equipment.Therefore

in thispaper the degradati

on process of EP in C

3

F

7

CN/CO

2

is studied by way of simulating the interface discharge.The sur-face morphology

roughness

composition of elements and chemical bonds and impulse flash-over voltage are mea-sured.Finally

the degradation mechanism of EP discharge is analyzed from the aspect of gas-solid interaction.It isshown by the result that the flash-over voltage of EP decreases with the increase of discharge time.Compared withthe new samples

the decrease is only about 0.3% at 50 h and up to 13.5% at 300 h.The surface morphology of EPafter interface discharge is basically the same of that in SF

6

.C-C

C=C and C-O bonds on EP surface are also easyto fracture and F·is easy to replace H·

introducing a large number of C-F bonds on the surface of EP.However

the CH

3

·is easily replaced by C≡N on the surface of EP.The formation of product C

12

F

7

H

17

O

2

indicates that the EPdischarge degradation is serious.