The Belt and Road Initiative (BRI) is a new model of international cooperation and new platform for global governance under contemporary international law. The Initiative will promote basic principles of international law, playing the mediating role of preventing disputes and resolving various risks in the process of establishing a new pattern of global governance. The Initiative is in line with the new trend of international cooperation and development in the 21st century, representing a new round of the process of reforming international political economy. It is a useful attempt to enhance China’s contribution to economic co-prosperity and political stability among the countries along the Belt and Road. This paper tries to understand the BRI under contemporary international law. Part two will discuss the status of the BRI. Part three will investigate the influence of the BRI. Part four will analyze the function of contemporary international law for co-building the Belt and Road.