Based on the gradual promotion of carbon market pilot as an exogenous event, this paper uses a multi-period triple difference model to explore the impact of carbon market on the audit pricing of high-carbon enterprises. It is found that the establishment of carbon market will have a positive spillover effect on audit pricing, which supports the Porter hypothesis from the perspective of audit pricing. The policy dynamic effect shows that after excluding the expected effect of policy, the carbon market has an impact on audit pricing in the current period and shows a strengthening trend. The mechanism test shows that the carbon market affects audit pricing through signal effect channels and green transformation channels, and the marketization level and regional environmental awareness can further strengthen the spillover effect of the carbon market on audit pricing, and also exclude the audit opinion purchase hypothesis. The heterogeneity analysis shows that there are different and asymmetric impacts in different industries covered by the carbon market and different carbon market pilot areas.