Abstract: In the early developing period, the enterprises need permanent support from angle investment and risk investment. However, China has big problems in this area. As a result, government should actively guide the private capital. In overseas, a lot of countries gave the permanent investors of the minor enterprises tax preference to stimulate the private capital. Because China’s present income tax system is not power enough to stimulate the permanent investment in science and technology, and the problems as “heavy back-end, short term” that equity investment encouragement has, this article will give some suggestions on tax policy.