In order to study the working frequency insulation characteristics of N

2

/O

2

gas mixtures with different ratios and analyse the influence of O

2

on the insulating properties of the gas mixtures

this paper calculates the critical electric fields of N

2

/O

2

gas mixtures with different ratios based on the electron transport parameters based on the Boltamann equation

comparing the Wieland approximation with the Garland approximation

and analyses the influence of O

2

on the insulating properties of the gas mixtures. The influence of O

2

on the insulating properties of the gas mixture is analysed. Meanwhile

the frequency discharge test of N

2

/O

2

gas mixture with 5%-21% O

2

ratio under 0.1-0.8 MPa is carried out

and the reliability of the calculation results is verified by combining with the test data. It is found that the O

2

ratio has almost no effect on the frequency insulation characteristics of N

2

/O

2

gas mixtures within the range of test ratios

and that the air pressure is linearly correlated with the discharge voltage of gas mixtures. The article can provide reference for the design

operation and maintenance of clean air power equipment.