Network perspective is one of the important methods of financial center research. Network is a social and economic structure，which connects people，enterprises and places，so that knowledge，capital and goods can circulate in space. In the era of globalization and information technology，the financial center is a city in the hub position in the networks at all levels. It is not only its own financial strength that determines the status of the financial center，but its external connection is particularly important. Cities with strong external connection are often in the hub position in the global financial network. Since the 1980s，the practice of neoliberal economic thought，the spread of English culture and global immigration have made London a real global city. The network of world cities and financial centers centered on London has touched the world’s major economies. In addition，the establishment of the EU has accelerated the integration process between London and European cities，making London a real financial center in Europe，the European headquarters of many multinational financial giants and the largest trading center of the euro. However，brexit has destroyed the development mechanism of the city of London，cut off many external links and channels，and many financial institutions have transferred jobs to other cities in the EU. London’s experience and lessons show that in the context of double circulation，the key to building an international financial center in Beijing is to build a node of domestic circulation and a portal of international circulation with CBD as the core，and form its own financial hinterland and financial network.