The relationship between digital transformation and audit fees was empirically examined using a sample of Shenzhen and Shanghai A-share listed companies. It is found that digital transformation leads to a significant increase in audit fees.Good internal control and firm size can negatively modulate the positive correlation between digital transformation and audit fees.Heterogeneity analysis shows that the positive correlation between digital transformation and audit fees is more significant for non-asset-intensive firms, non-heavily polluted firms, and high-tech firms. The conclusions will be able to provide certain experience for enterprises to promote digital transformation and help the flourishing development of digital economy.