In this paper

hexafluoropropylene（1-C

3

F

6

）

a kind of new environmentally friendly insulating gas

is in-troduced and the insulation characteristic of 1-C

3

F

6

/CO

2

gas mixture under different electrode structures and voltagecharacteristics is st

udied in particular.It is shown by the study that in the uniform electric field

the 50% breakdownvoltage of 1-C

3

F

6

/CO

2

gas mixture increases with the increase of electrode distance and gas pressure

and the powerfrequency breakdown voltage approximates linear rise with the rise of gas filling pressure.The power frequencybreakdown voltage of pure1-C

3

F

6

gas at pressure of 1.25 bar is close to that of SF

6

.In addition

the power frequencybreakdown voltage of 1-C

3

F

6

/CO

2

gas mixture is higher than that of the C

5

F

10

O/air gas mixture at various gas fillingpressures.While

in slightly non-uniform electric field

the DC and power-frequency breakdown voltage of 1-C

3

F

6

/CO

2

gas mixture increases rises with the rise of gas filling pressure and shows better linearity.In case of extremelynon-uniform electric field

the power frequency breakdown voltage of 1-C

3

F

6

/CO

2

gas mixture rises gradually withthe rise of gas filling pressure and tends gradually to saturation.The test result in this paper can provide referenceand basis for the design of power products.