A passive optical network (PON) system includes at least one optical line terminal (OLT), a plurality of optical network units (ONUs) connected to each OLT, and an OLT management server used to manage the OLT. The OLT management server creates a VLAN access control table in response to a user's request to indicate a VID translation relation among different VLAN identifiers (VIDs) and sends a VID translation relation described in the VLAN access control table to the OLT, and the OLT creates a VLAN translation table indicating a correspondence relation between a source VID and a destination VID, which are waiting for translation, based on the received VID translation relation. If the OLT determines that a VID included in a received frame must be translated based on the VLAN translation table, the OLT references the VLAN translation table to translate the VID included in the received frame to a corresponding destination VID.