Digital transformation plays a critical role in driving businesses to achieve operational efficiency， enhance market competitiveness and promote long-term sustainable growth. However， the impact of digital transformation on CSR is not yet fully clear， especially when considering the contradictory relationship between legitimacy pressure and principal-agent issues. It aimed to explore the complex impact mechanism of digital transformation on CSR under the combined effect of legitimacy pressure and principal agent， as well as the heterogeneous performance in the context of controlling shareholders’ equity pledges. Based on legitimacy theory and principal-agent theory， hypothesis testing was conducted on a sample of Chinese Shanghai and Shenzhen A-share companies from 2010 to 2021. The results show that digital transformation is significantly and positively related to symbolic CSR， while it has an inverted U-shaped relationship with substantive CSR， and the higher the level of digital transformation， the more serious the decoupling of CSR. Firms with controlling shareholders’ equity pledges have more serious principal-agent problems， and tend to take advantage of the asymmetric information and manipulability of CSR reporting to conduct symbolic CSR， rather than fulfilling substantive CSR， which exacerbates the decoupling of CSR； firms without controlling shareholders’ equity pledges take into account both substantive and symbolic CSR，so the decoupling phenomenon is not obvious. Further differentiating between nature of the enterprise is tested and the principal-agent mechanism still holds. The conclusion enriches the theoretical framework of the relationship between digital transformation and CSR under paradox management， reveals the heterogeneous performance of CSR under the dual roles of legitimacy pressure and principal-agent， as well as the paradox management strategy， and provides new ideas for further explaining the complex paradoxical relationship.