The Maritime Silk Route plays an essential role in the sustainable development of China's economy and society, and is one component of the "Belt and Road Initiative" construction. Southeast Asia is a main area in building the Maritime Silk Route. Going back to ancient times, the problems of thoroughfare security once caused the decline of the Maritime Silk Route. We still face severe security issues in building the maritime thoroughfare in the present century, and this is critical for the success of the new Maritime Silk Route. There are both traditional and non-traditional security foundations for the construction of the 21st Century Maritime Silk Route; we need to maintain a good relationship with the U.S., crack down on the existence of terrorism, achieve proper resolution of territorial disputes in the South China Sea, and actively build a non-traditional security cooperation mechanism.