In his Explanatory Notes for “the Decision of the Central Committee of the Communist Party of China on Some Major Issues Concerning Comprehensively Deepening Reform，” Xi Jinping，the general secretary of the Party points out that，“currently，we are challenged by pressure from two sources：internationally we must safeguard state sovereignty，national security and development interests，and we need to maintain political security and social stability. All kinds of foreseeable and unforeseeable risks are increasing significantly，but our security system is not good enough to meet the demands of ensuring national security.” Hence，it is imperative to establish and improve China’s national security system. This article will discuss the intrinsic meaning and historical changes and developments of China’s national security system，the existing problems within it and measures to be taken for its improvement.