An Ethernet data reassembly apparatus comprises: a data receiving unit, for receiving the data of a gigabit passive optical network frame; a data reassembly unit, for storing the data of the gigabit passive optical network frame into the corresponding location of a data buffer unit, based on the Ethernet data intermediate variable stored in a data reassembly table unit; a data reassembly table unit, for storing the Ethernet data intermediate variable; and a data buffer unit, for storing the data of the gigabit passive optical network frame received by the data receiving unit, to acquire integrated Ethernet data. A method comprises the following steps: receiving the data of a gigabit passive optical network frame; storing the data of the gigabit passive optical network frame into the corresponding location of a data buffer unit, based on the Ethernet data intermediate variable stored in a data reassembly table unit. According to the present invention, ONU and OLT could perform an interleaving process for any number of data frames.