The embodiment of the invention discloses a method and a device for transmitting data. The method comprises the following steps: receiving data transmitted to a home address of a mobile node; searching a binding relationship between the home address and a care-of address of the mobile node; transmitting the data according to the binding relationship; and transmitting the binding relationship to aformer hop router. In the embodiment of the invention, the received data transmitted to the home address of the mobile node is directly transmitted to the care-of address of the mobile node through the binding relationship between the home address and the care-of address, so that the data does not need to be transmitted to the home address first and then transmitted to the care-of address from the home address, data transmission routes are decreased, network data transmission quantity is reduced, and network congestion is avoided.