Abstract: Digital transformation is an important part of digital economic development in China. It largely promotes the integration of digital economy and the real economy, and gives China important advantages in the new round of international competition. Using the data of A-share listed companies in Shanghai and Shenzhen stock markets from 2011 to 2021, the relationship between the digital transformation and customer concentration, as well as their channel mechanisms, was empirically tested. The results show that with the improvement of the degree of enterprise digital transformation, customer concentration will be significantly reduced. In this process, digital transformation enhances the ability of enterprises to improve the ability and motivation to disclose high-quality information. The improvement in information disclosure quality will further alleviate the pressure brought by overly concentrated customer resources on the enterprise. In addition, for enterprises with high sales expense ratio and earnings management, low total factor productivity and analysts’ attention, and non-state-owned enterprises, digital transformation can attract more customers and reduce customer concentration. At the same time, compared with the provinces where the development of digital economy is still relatively backward, enterprises in areas with high development level of digital economy are more likely to significantly reduce their dependence on large customers through digital transformation. Finally, it is found that digital transformation can improve the market position after reducing customer concentration.