The present invention discloses a device and method for data matching and a device and method for network intrusion detection. The method for data matching includes: searching in a regular expression set one or more complex regular expressions causing a sharp increase in number of states generated based on a regular expression during interaction; constructing a corresponding simplified expression for each complex regular expression; compiling a simplified state machine; compiling one or more substate machines, wherein each of the one or more substate machines is compiled based on a corresponding one of the one or more complex regular expressions; and matching data based on the simplified state machine and the one or more substate machines. The present invention further discloses a device for data matching employing the method for data matching and a device and method for intrusion detection employing the device and method for data matching.