Due to the rapid expansion and advancements of computer network, security has become a vital issue for modern computer network. The network intrusion detection systems play the vital role in protecting the computer networks. So, it has become a significant research issue. In spite of notable progress in intrusion detection system, there are still many opportunities to improve the existing systems in terms of false positives and classification accuracy. This paper is to reduce the false positive and increase the classification accuracy of intrusion detection system.