Abstract: In China, public R & D departments supported by the government (mainly including colleges,universities and scientific research institution) and enterprises constitute the social R&D system. In this system, the changes of government R & D funding will affect the leverage effect of public R&D investment. This paper starts from the perspective of social R&D system,uses FGLS method with the provincial panel data of industrial enterprises in 2009-2013 to explore the change of leverage effects,which caused by government R&D funding changes.The study found that there is a difference between the leverage of public R & D investment in different areas. At the place where the enterprises are highly supported by government R&D funding,it will have a positive effect on promotion of enterprise R&D investment when government supports colleges and universities,but also have a negative effect on promotion of enterprise R&D investment when government supports scientific research institution.However,where the enterprises are lowly supported by government R&D funding,the impact is completely opposite. Therefore, all the governments should pay attention to the precision of investment in public R & D investment and use policy tools in a reasonable way.