Although a lot of achievements have been acquired in building China' s National Innovation System,there are still rooms for improvement such as lack of coordination in measures adopted by government departments to support companies' technology innovation,failure of enterprises to become the real main player of technology innovation,loose cooperation between industry-university-research entities,etc.By researching on the concept and inner composition of National Innovation System of China,this paper aims to analyze the current status and weak points of China's National Innovation System,expound the priorities and trends of National Innovation System,which covers the technology innovation system,the knowledge innovation system,the defense science and technology system,the regional innovation system and the science and technology agency service system.The technology innovation system has the following functions:1) companies act as the main player and industry-university-research entities cooperate well;2) the knowledge innovation system operates as science research entities and higher education institutions cooperate closely.3) the defense science and technology innovation system works taking both military and civil needs into account;4) the regional innovation system carries unique comparative advantages and distinctive features;5) the science and technology agency service system runs as highly socialized and network-oriented.