Embodiments of this application relate to the field of communications technologies, and disclose a flow control method and apparatus, to resolve a prior-art problem such as packet loss, packet accumulation, or network congestion that occurs after a packet is switched between priority queues. A specific solution is as follows: A first device receives a first packet sent by a second device, where the first packet carries a first field and a second field, the first field carries a first priority, and the second field carries a second priority; the first device performs flow control based on the first priority in the first packet; and the first device performs queue scheduling on the first packet based on the second priority in the first packet.