The invention discloses a method and a system for setting detection frame timeout duration of an Ethernet node. The method comprises the steps of: when the Ethernet node determines that a communication port maintains a connected state or changes to a non-connected state from the connected state, setting the detection frame timeout duration of the communication port as a value within a first time range; and after the Ethernet node detects that the communication port changes to the connected state from the non-connected state, setting the detection frame timeout duration of the communication port as a value within a second time range, wherein the value in the second time range is larger than the value in the first time range. The manner for setting the detection frame timeout duration of the Ethernet node in the present invention can prevent the waste of bandwidth caused by data cycle due to closed loop of a network, thereby node communication is ensured while preventing the closed loop from being formed again, and the network performance is improved. The present invention can further detect a loop forming point, and the network maintenance is facilitated.