An embodiment method includes: mapping a to-be-transmitted optical channel unit signal of n times a benchmark rate to X first optical channel physical link signals; adding a link sequence indicator overhead to each of the X first optical channel physical link signals, to generate X second optical channel physical link signals; and modulating and sending the X second optical channel physical link signals by using X preset optical modules in a one-to-one manner. A rate of the first optical channel physical link signal is mi times the benchmark rate, n≥2, X≥2, mi≥1, and ∑ i = 1 X ⁢ m i = n .