An aggregation node device of a passive optical network (PON) is provided which includes an aggregation optical line terminal (OLT) and an aggregation optical network unit (ONU). The aggregation OLT is connected to a user-side ONU. The aggregation OLT aggregates service data transmitted by a user-side ONU and transmits the aggregated service data to the aggregation ONU. The aggregation ONU is adapted to transmit the received aggregated service data to a network-side OLT. A PON system is further provided. The device and system can not only support the conventional time division multiplexing (TDM) services but also support the services based on variable-length packets and the multicast service. Moreover, it is not necessary to build an equipment room and supply power for an intermediate optical distribution network (ODN) which greatly reduces the network construction and operation costs.