Provided are a multi-pattern policy detection system and method, wherein, in an environment that operates a plurality of policies for determining matching or non-matching by a string or a normalized format, the plurality of policies are expressed by a data structure that is searchable at a time, and are optimized to improve search performance. The multi-pattern policy detection system includes: a search front stage optimizer configured to register a string of a signature fragment received from a signature fragment list as a registration pattern of a front stage of a signature by taking into account length and uniqueness of the string; a search rear stage optimizer configured to receive the signature fragment from the signature fragment list, and register the signature fragment as a registration pattern of a rear stage when there is no registration signature fragment of the rear stage; and a detection engine configured to perform attack detection by using the front stage of the search front stage optimizer and the rear stage of the search rear stage optimizer.