Embodiments of the present invention disclose a method for processing network congestion. A first switch obtains total traffic that is received by a receiving port communicating with a third switch. The total traffic includes traffic that is occupied by a data flow sent by a second switch, and the first switch. When the first switch determines, according to the total traffic, that a sending port of the third switch is congested, the first switch determines a target port. The target port is another port that can receive the data flow and that is selected from receiving ports of the first switch. The first switch sends an adjustment message to the second switch. The adjustment message carries an identifier of the data flow and an identifier of the target port, and the adjustment message is used by the second switch to send the data flow to the target port.