This article traces the development process of Beijing’s First Green Belt from its origins in the 1950s, to its reinterpretation in the 1980s/1990s and its implementation in the 1990s/2000s. We identify three-time phases and important milestones, which kept the green belt idea alive, developed it and contextualized it in relation to the historical background. This article shows that the first green belt project in Beijing was a continuing process of changing functions and ranges. Its adaptability to variations followed the political changes and reflected the socio-economic dynamics, which secured its longevity. Different ideas shaped the plan and its link to mega events like the Olympic Games and environmental problems accelerated the implementation, but the shortage of funding and absence of legislation led to a compromised result. The case is an interesting example of how a long-term project transforms over and with time, but also for the gap between planning ambitions and actual urban development, illustrating past and contemporary urban planning in the context of a fast-developing country.