Method and an apparatus are provided for indicating a fault status. The method includes: a first device determines N alignment marker AM groups, where the N AM groups include first indication information, the first indication information is used to indicate a fault status of R receiving logical lanes of the first device, and each of the N AM groups includes M pieces of alignment marker group lane AMGL information; and in an ith period of N periods, the first device respectively sends M pieces of AMGL information constituting an ith AM group to a second device over M transmitting logical lanes.