This application discloses: collecting statistics about a target parameter of a first data flow, where a target queue of a switching device is used to buffer a data packet in at least one data flow, the first data flow is one of the at least one data flow, and the target parameter is used to reflect an amount of data in the first data flow; when a length of the target queue meets a first length condition, determining, based on at least one of the target parameter and an auxiliary parameter of the first data flow, a marking probability corresponding to the first data flow; and performing congestion marking on a data packet in the first data flow based on the marking probability corresponding to the first data flow.