Beijing has superior conditions for developing digital economy，and is the forerunner and leader of China’s digital economy development. In recent years，Beijing has introduced a series of measures to support the development of digital economy，and established the grand goal of building a global digital economy benchmark city. The digital economy is developing rapidly. This part first reviews the different stages of Beijing’s development of digital economy since 1990s. Secondly，it systematically reviews the achievements of Beijing’s digital economy development from the aspects of digital economy scale，development of digital economy-related services and manufacturing industries，digital infrastructure construction，digital governance application，digital economic policies，etc. Thirdly，using enterprise big data to evaluate the development of digital economy service industry in Beijing in recent 20 years；Fourthly，the experiences of London，New York and Shenzhen，three world-famous cities that are at the forefront of digital economy construction，are introduced in detail，which can provide reference for Beijing to develop digital economy.