During China’s rapid urbanization, its megacities are facing the greatest challenge of urban growth control of both population and built-up area. As one of the most important measures of urban containment, Green Belt has been widely used worldwide for many years. Beijing’s Green Belts have been in their implementation for nearly three decades, during which different implementation modes were used. The article looks into the evolution of Beijing’s Green Belts policies and the existing implementation modes, in which, the government, rural collectives and property developers cooperate in different ways. The aim of the article is to provide China’s megacities with experience and lessons of urban containment policy implementation. In-depth interview, fieldwork, document research, remote sensing and GIS analysis are used for summarizing the detailed processes of different implementation modes, as well as their strengths and weaknesses. The four modes involved include ‘government direct participation – property developer nonintervention’, ‘government direct participation – property developer intervention’, ‘government nonparticipation – property developer intervention’ and ‘government indirect participation – property developer intervention’. Typical areas in the unit of township are selected to analyze and compare the effectiveness of Green Belts policy under different implementation modes. The conclusion is that the implementation mode of ‘government direct participation - property developer nonintervention’ results in the greatest effectiveness of physical environmental plan implementation, but requires large amounts of financial expenditure, and thus cannot be widely used. The mode of ‘government nonparticipation – property developer intervention’ suits market-oriented economy best, and thus is most widely used, but it has also left many unsolved problems caused by market failure such as capital chain rupture. Suggestions for policy improvement lie in how to guide these four modes respectively to achieve the multiple goals more effectively during Beijing’s Green Belts implementation.