A method for solving a mismatched negotiation result between an auto-negotiation mode and an enforce mode in an Ethernet. The method is applied to a local device with an auto-negotiation mode, the local device is connected to a remote device, and the local device has a plurality of registers including at least an auto-negotiation advertisement register (ANAR) for recording information advertised to the remote device by the local device, and an auto-negotiation link partner ability register (ANLPAR) for recording an ability of the remote device. First, turn on the auto-negotiation mode. The contents of the ANAR register are set according to a transmission mode enforced by a user when the remote device is in the auto-negotiation mode, and then the auto-negotiation mode is restarted. Next, the contents of the ANAR and the ANLPAR registers are determined whether they are matched. If the contents of the ANAR and the ANLPAR registers are matched, then the local and the remote devices are normally connected; otherwise, the local and the remote devices are disconnected.