关键词: 入侵检测, 模式匹配, Boyer-Moore（BM）算法, 字符串检索

Abstract: Pattern matching algorithm is an important algorithm，used by most of Intrusion Detection System.On the base of analyzing BM algorithm and other algorithms，a new improved pattern matching algorithm—BMI algorithm is presented.The algorithm makes reference to the idea of BM algorithm and makes use of singleness and combination of the last character and next character of string，increasing the probability of maximum displacement effectively.Test results show that the algorithm can effectively improve the efficiency of the matching process.

Key words: intrusion detection, pattern matching, Boyer-Moore（BM） algorithm, string searching