It’s very difficult that the traditional intrusion detection methods based on accurate match adapt to the blur and uncertainty of user information and expert knowledge, it results in failing to report the variations of attack signature. In addition security itself includes fuzziness, the judgment standard of confidentiality, integrity and availability of system resource is uncertain. In this paper fuzzy intrusion detection based on partial match is presented to detect some types of attacks availably and alleviate some of the difficulties of above approaches, the architecture of fuzzy intrusion detection system (FIDS) is introduced and its performance is analyzed.