The development of digital economy has become an important choice around the world for driving economic development，and it is also the key to building a dual-cycle economic development pattern in China. Therefore，it is practically significant to study the development of digital economy in the three major urban agglomerations in the east. This report firstly makes a comparative analysis of the development of digital economy in the three major urban agglomerations in the east from the aspects of total volume，structure，gap and innovative output. Then，a panel regression model is constructed on this basis to further analyze the influencing factors of the digital economy of these urban agglomerations. The study found that the registered capital of the digital service enterprises of Beijing-Tianjin-Hebei urban agglomeration ranks first in the three major urban agglomerations in the east，and Beijing has a dominant position significantly. Compared with the Yangtze River Delta and Pearl River Delta，Beijing-Tianjin-Hebei urban agglomeration has obvious advantages in the development of digital information transmission industry，and the imbalance of digital economy development among cities is more prominent. The innovative output of digital service industry in Beijing-Tianjin-Hebei urban agglomeration is at a high level relatively，and the number of utility model patents in digital technology service industry ranks first. Industrial structure，innovation development level and government support are the key factors affecting the development level of digital economy in Beijing-Tianjin-Hebei urban agglomeration. On this basis，this study puts forward countermeasures and suggestions for the development of the digital economy in Beijing-Tianjin-Hebei urban agglomeration.