The present application provides data transmitting and receiving methods and devices for an Optical Transport Network (OTN). The service transmitting method for the OTN includes that: Optical Data Unit (ODU) services are mapped into cells of a payload area of an OTN interface frame, the payload area including N cells with a fixed size, one cell being used for carrying one ODU service and N being an integer larger than or equal to 1; and the OTN interface frame is encapsulated and transmitted.