Sulfur hexafluoride（SF

6

） has excellent insulation and arc quenching properties and is widely used in electric power equipment. However

this gas is a strong greenhouse gas

and has been required to be restricted or even stopped. Carbon dioxide（CO

2

） has excellent arc extinguishing performance

and it has a great application prospect instead of SF

6

gas as a potential arc extinguishing medium. Consequently

we focused on the application of CO

2

gas in high-voltage gas circuit breakers

and analyzed the post-arc breakdown characteristics by magnetohydrodynamic arc simulation and post-arc thermal and electrica

l breakdown characteristics. Moreover

we discussed the feasibility and key issues of using CO

2

gas as the arc extinguishing medium of high-pressure gas circuit breaker. The results show that the arc thermal interrupting capability of CO

2

under the present circuit breaker structure is about 28.7% of SF

6

gas; the rise rate of recovery voltage of CO

2

gas during post arc is slower than that of SF

6

gas

and the probability of dielectric breakdown at the front end of moving contact is higher; Elevating gas pressure can effectively improve the arc thermal interrupting capability and recovery strength during post arc. This study can provide references for the development and optimization of environmentally friendly high-pressure gas circuit breakers.