With the development of computer technology, the network scope has been expended, and the security protection has become more and more important and complex, amount that, network security has received more attention. IDS(Intrusion Detection System) is a new generation of security technology after the traditional security measures, such as firewalls and encryption. And how to evaluation and test of an IDS becomes more important. This paper describes segmented and multi-level mixed evaluation methods, in the evaluation, classifies intrusions by type of TCP/IP, and illustrates the evaluation process by means of the Deterministic Finite Automaton (DFA) in fragmentation, making the test process more visualized and vivid. Meanwhile, credibility levels are assigned to measures taken to make products meet basic function requirements.