Abstract: As the most active part of China's current economic development, digital economy is the backbone and guarantee to lead high-quality economic development in China. However, existing studies have paid little attention to the relationship between digital economy and regional integration development. Theoretical analysis shows that digital economy can promote regional integration through direct transmission mechanism and indirect mechanism of optimizing regional industrial structure, and this process exhibits threshold effect and spatial spillover effect. This paper measures the comprehensive level of digital economy, industrial structure and regional integration of the Guangdong-Hong Kong-Macao Greater Bay Area and its hinterland cities from 2010 to 2019, and makes an empirical analysis by using regression analysis method. The results show that, the transmission mechanism of digital economy's positive impact on regional integration development and the two major effects in the influence process are consistent with the theoretical analysis. Finally, this paper puts forward some suggestions: increasing investment and construction of Internet infrastructure, promoting digital transformation of traditional industries, perfecting national innovation system, and strengthening cooperation between local governments and enterprises.