A multicasting method and apparatus in a network including a transport multiprotocol label switch (T-MPLS) network and a wavelength division multiplexing (WDM) network are disclosed. At least one of first switches, connected to the T-MPLS network, second switches connected to the WDM network, and a switch hub establishes a multicasting path by using a label switch path (LSP) ID and a label switch router (LSR) ID, in which the first switch on the multicasting path multicasts a T-MPLS signal, the switch hub converts the T-MPLS signal into an optical multicasting signal and multicasts the converted optical multicasting signal, and the second switch receives the optical multicasting signal and multicasts it in units of the T-MPLS signal.