The present disclosure discloses a direct-link quality monitoring method, communications device, and system, where the method includes: determining, by a local device after establishing a neighbor relationship with a peer device, whether a quantity of neighbors of the local device is the same as a quantity of neighbors of the peer device; if the quantity of neighbors of the local device is different from the quantity of neighbors of the peer device, electing a device, either the local device or the peer device, with a larger quantity of neighbors as a measurement control point MCP of a direct link between the local device and the peer device; and executing a corresponding monitoring operation according to whether the local device is the MCP of the direct link, so as to monitor quality of the direct link together with the peer device.