On the basis of providing the definition of public security system, this paper puts forward the concept of public security comprehensive index, discusses the characteristics of uncertainty and the method of system non-optimum analysis, at the same time, it establishes the running system of public security. Based on the security index, it provides the index of public security control ability and discusses the analysis method of uncertain factor. Studies have shown that the scientific and technological contribution rate of public security is the key to the scientific and technological strategic research. This paper also sets up the function between science and technology input and public security target, discusses the relationship between input and output of science and technology contribution increase ratio, and finally establishes basic thinking of public security science and technology research system and research planning.