Building the 21st Century Maritime Silk Road is a new initiative for international cooperation. It will have a positive impact on the peaceful use of the South China Sea by encouraging a Code of Conduct to Parties in the South China Sea between China and ASEAN members; realizing a breakthrough of jointly developing oil and gas resources in the area; promoting comprehensive cooperation in maritime non-traditional security field; and providing a peaceful external environment for the South China Sea dispute settlement. The South China Sea dispute is a negative challenge to building the 21st Century Maritime Silk Road. However, the pace building should not be stopped because of it. In the future, the 21st Century Maritime Silk Road will be on the international consensus as an international legal regime. Also, it will improve the domestic legal system regarding building the 21st Century Maritime Silk Road for China as well as the countries along the Belt and Road, especially the ASEAN members.