Efficiency scores of the National Innovation System (NIS) for 22 countries, including the BRICS, G7, are calculated with the Data Envelopment Analysis (DEA). Relevant factors that may affect the innovation system efficiency are summarized based on the NIS Approach and the New Growth Theory. Empirical study is further made with the Panel Data Analysis (PDA) and the Principal Component Analysis. The results of efficiency calculation and empirical test show that: (1) The BRICS differ greatly in the efficiency of NIS, with China, India and Russia ranking fairly high, and Brazil, South Africa among the few bottom; (2) The influencing factors involve a lot of elements, including the ICT infrastructure, enterprise R&D, market environment, government governance, education system, economic scale, natural endowments, external dependence, which is conformed to the NIS approach and New Growth Theory; (3) Enterprises innovation activities are of key importance to the NIS. To improve the efficiency of the innovation system, efforts should be made to improve the market circumstance, governance, and financial structure, and create a sound environment for innovation. (4) ICT infrastructure, economic scale and openness affect the diffusion of knowledge and technology, and in turn the NIS efficiency. (5) The BRICS have characters of low governance level and high natural resources dependency in common, which is determined by their developing stage and extensive growth pattern. To avoid the so called middle-income trap in the coming future, the BRICS should dedicate to transform the factor-driven pattern to an innovation-driven one. As for China, there is still much to be improved in the fields of ICT infrastructure, government governance, education system. During the 12th Planning, more efforts should be put into these fields and make better external conditions for innovation activities
