Abstract: A network congestion handling method is provided. The method is applied to an HPC cluster including a plurality of hosts, and the plurality of hosts are connected via a network device. A transmit end obtains a first acknowledgment message including a network congestion scenario identifier. The network congestion scenario identifier is an identifier indicating a scenario in which network congestion occurs in a process in which the transmit end transmits data to a receive end, and the transmit end and the receive end are any two hosts in the plurality of hosts. Then, the transmit end adjusts a data sending rate of the transmit end based on the network congestion scenario identifier.