Hackers' attacks are more and more intelligent, which makes it hard for single intrusion detection methods to attain favorable detection result. Therefore, many researchers have carried out how to combine multiple security measures to provide the network system more effective protection. However, so far none of those methods can achieve the requirement of the practical application. A new computer information security protection system based on data fusion theory is proposed in this paper. Multiple detection measures are \"Fused\" in this system, so that it has lower false negatives rate and false positive rate as well as better scalabilities and robust.