A method for multiplexing and mapping services to an Optical channel Transport Unit (OTU) includes: filling the service data into a container block covering an Optical channel Payload Unit (OPU) area container having at least one frame. The container block includes at least one OPU area container having a frame. The OPU area container is composed of at least one OPU area sub-timeslot, and is configured to fill the service clock information into the Optical Channel Payload Unit Overload (OPU OH) area. A device for multiplexing and mapping services to an OTU is provided in an embodiment of the present invention.