Embodiments of this application provide a link fault monitoring method and related apparatus, and the method includes: A network monitoring device obtains a poor-quality parameter of a target link segment, where the poor-quality parameter is a proportion of the quantity of abnormal terminal devices in the target terminal devices that transmit data by the target link segment; and the network monitoring device determines, based on the poor-quality parameter, whether the target link segment is a faulty link segment. The embodiments of this application provide a technical solution that facilitates monitoring a potential faulty link segment in a network link.