A packet control method, comprising: detecting at a current node a packet flow causing a congestion status change, wherein a packet in the packet flow is received from an upstream node; generating by the current node a congestion isolation message, sending the congestion isolation message to an upstream node that sends the packet flow to the current node, wherein the congestion isolation message is used to instruct the upstream node to reduce a scheduling priority of the packet in the packet flow, and the congestion isolation message comprises description information of the packet flow; and characterized by further comprising: setting, to a first mark, content of a congestion mark item in an entry that corresponds to the packet flow and that is in a flow table, wherein the congestion mark item is used to record whether a packet flow corresponding to an entry to which the congestion mark item belongs is a congestion flow, and the first mark is used to indicate that the packet flow corresponding to the entry to which the congestion mark item belongs is a congestion flow; and if no packet in the packet flow is received within predetermined duration starting from a moment recorded by a timestamp item in the entry, setting the mark item to a second mark, where the second mark is used to indicate that the packet flow corresponding to the entry to which the mark item belongs is a non-congestion flow, and the timestamp item is used to record a moment at which a packet in the packet flow is last received. detecting at a current node a packet flow causing a congestion status change, wherein a packet in the packet flow is received from an upstream node; generating by the current node a congestion isolation message, sending the congestion isolation message to an upstream node that sends the packet flow to the current node, wherein the congestion isolation message is used to instruct the upstream node to reduce a scheduling priority of the packet in the packet flow, and the congestion isolation message comprises description information of the packet flow; and characterized by further comprising: setting, to a first mark, content of a congestion mark item in an entry that corresponds to the packet flow and that is in a flow table, wherein the congestion mark item is used to record whether a packet flow corresponding to an entry to which the congestion mark item belongs is a congestion flow, and the first mark is used to indicate that the packet flow corresponding to the entry to which the congestion mark item belongs is a congestion flow; and if no packet in the packet flow is received within predetermined duration starting from a moment recorded by a timestamp item in the entry, setting the mark item to a second mark, where the second mark is used to indicate that the packet flow corresponding to the entry to which the mark item belongs is a non-congestion flow, and the timestamp item is used to record a moment at which a packet in the packet flow is last received. setting, to a first mark, content of a congestion mark item in an entry that corresponds to the packet flow and that is in a flow table, wherein the congestion mark item is used to record whether a packet flow corresponding to an entry to which the congestion mark item belongs is a congestion flow, and the first mark is used to indicate that the packet flow corresponding to the entry to which the congestion mark item belongs is a congestion flow; and if no packet in the packet flow is received within predetermined duration starting from a moment recorded by a timestamp item in the entry, setting the mark item to a second mark, where the second mark is used to indicate that the packet flow corresponding to the entry to which the mark item belongs is a non-congestion flow, and the timestamp item is used to record a moment at which a packet in the packet flow is last received.