Abstract:According to the overall requirements of further enriching and improving the national innovation system (NIS), it is urgent to strengthen the relevant theoretical research of the innovation system. By the methods of theoretical and comparing analysis, this paper traces the evolutions of innovation system theory and the characteristics of NIS construction for different stages, and then summarizes the corresponding key points and the main measures for NIS construction under the different perspectives of "actors-framework", "activities-function", and "system-ecology". Besides, based on the deployment requirements of China that China has entered the stage of high-quality development, entered the forefront of an innovative country in the future, and become a strong country of science and technology, the paper puts forward four policies and measures to further enrich and improve China's national innovation system in the new era: policy-oriented transformation from improving the innovation system to forming an innovation ecology; forming a dynamic and thriving main cluster of innovation actors; promoting the efficient flow of innovation elements and values; forming a institutional and a cultural environment to support the innovative ecology.