The embodiment of the invention discloses a message classification method and a system, wherein, the method comprises the following steps: a domain search engine is utilized for carrying out domain division processing to a message to be inquired; a polymerization network is utilized for carrying out progressive polymerization to a domain division processing result until a destination node, wherein in the process of progressive polymerization, each polymerization mode is polymerized through two-stage matching logic; and according to a tuple hit by the destination node, classification rules matched with the message to be inquired is determined. Through conversion of a rule base into a domain division tuple base, the embodiment of the invention greatly reduces the memory consumption of the polymerization network, thus leading the method provided by the embodiment of the invention to be extensively adaptive to large scale classification rule bases.