The present invention discloses an apparatus for collecting charging information of data service and charging method thereof. The apparatus comprises: a protocol distribution processing module, for classifying service data received from a gateway service node in the wireless network by the protocol type, and sending the classified service data to a protocol processing module of the corresponding protocol type; receiving service data from said one or more than one protocol processing module and sending the service data to the gateway service node; at least one protocol processing module, for receiving the classified service data from the protocol distribution processing module, obtaining charging information of the service data and sending the charging information to a charging system, and transparently transmitting the service data to a packet switched domain network; receiving the service data from a packet switched domain network, obtaining the charging information of the service data and sending the charging information to the charging system, and transparently transmitting the service data to the protocol distribution processing module. This invention can accurately collect the charging information of service data of various classes.