A method for implementing fault detection includes: instructing, by a detection device, a detected device to configure a detected path and a return path, where the detected path is a path from a first physical port of the detected device to a second physical port of the detected device via a target unit of the detected device, the return path is a path from the second physical port to the detection device, and the target unit is a VNF or an accelerator; sending a detection packet to the detected device through the first physical port; and when receiving the detection packet transmitted through the detected path and the return path, determining that the detected path is not faulty. According to the method, it can be further determined that the path that passes through the VNF or the accelerator is not faulty.