The present invention provides a method, a data interface and a device for transporting data from a high-speed Ethernet to an OTN (Optical Transport Network), where seamless transport of Ethernet traffic to the OTN can be enabled through flow control, rate-matching, and mapping and encapsulation respectively performed at an Media Access Control Sub-layer, a Physical Coding Sub-layer, and an Optical Transport Network Interface Sub-layer. Thus, only one mapping and encapsulation of data is required to directly enable through a physical layer the transparent transport of the Ethernet traffic to the OTN, and due to the rate-matching implemented upon the mapping, the traffic transport can be enabled in a standard-compliant way with guaranteed efficiency and quality.