Based on the data from 1991 to 2003 released by the China Statistical Bureau, applied general Cobb-Douglas productivity function, this article takes empirical analysis on the relationship between science and technology investment and economic effect. The results show: science and technology investment not only brings about the present economic growth but also has retardation influence, and the retardation influence is only two years. its short behavior is very distinct. It is needed to not only pay attention to the gross but also to the structure and equipment and efficiency of the science and technology investment.