A fault detection method and device is disclosed. The method includes obtaining, by an optical transport network (OTN) device, a first OTN frame. The first OTN frame includes a plurality of payload areas. Each payload area includes payload check information and payload data. The method further includes performing fault detection, according to the payload check information, of payload data of a payload area in which the payload check information is located. The first OTN frame is divided into a plurality of payload areas, and corresponding payload check information is carried in each payload area.