This paper empirically investigates the potential determinants of R&D intensity using time serial data of China for the period of 1991-2007. A great number of factors potentially have an impact on the R&D intensity as discussed as following: Business sector, policy tools, public R&D sector, investment and economical factors. For the data obtained, twelve variables, including businesssector R&D intensity, business R&D human resource, industry structure, direct R&D subsidies of government, patent protection, public sector R&D, physical capital Investment, human capital, GDP per capita, rate of GDP growth, international trade and foreign direct investment, have been designed. Estimates using a partial adjusted model estimator controlling for endogeneity show a high degree of persistence in R&D intensity. Businesssector R&D intensity, industry structure, patent protection and investment have a significant and positive impact on R&D intensity.