The invention discloses a data mapping method and a data mapping device for an optical transport network. The method comprises the following steps: mapping packet service data or constant-bit-rate data to an ODUS and mapping the ODUS into an OTUS; and distributing the OUTS on a plurality of electrical channel signals, grouping the plurality of electrical channel signals and respectively mapping the electrical channel signals into corresponding OChSi, wherein the rates of the ODUS and the OTUS are N times of 100 gigabits per second, the rate of the OChSi is M times of 100 gigabits per second, the branch sequence sizes of the ODUS and the OTUS are 100 gigabits per second, N is a positive integer greater than or equal to 2, i is a positive integer, and M is a positive integer greater than or equal to 1 and smaller than N. By the adoption of the method and the device, a super 100G optical transport system can be deployed more flexibly by operators without being limited by fixed rate selection, and the optical fiber spectrum utilization efficiency and the flexibility and compatibility of a system are improved.