A method and a device for transmitting an Optical Channel Transport Unit signal are disclosed in the present invention. The method includes: receiving an Optical Channel Transport Unit OTUk signal after photoelectric conversion; wrapping the OTUk signal into an Optical Channel Data Unit (ODU) signal; multiplexing and mapping the ODU signal to an Optical Channel Payload Unit OPUj signal, where the OPUj signal is a High Order signal of the ODU signal; and wrapping the OPUj signal into an ODUj signal and an OTUj signal, and sending the ODUj signal and the OTUj signal. Through the embodiments of the present invention, fully transparent transmission of an OTU signal can be implemented.