Embodiments of this application provide a transmission path determining method and apparatus, where the method includes: determining that a current path corresponding to a flow to which a to-be-transmitted packet belongs is congested; and determining a target path for the to-be-transmitted packet based on a path congestion information table, and adding information about the target path to the to-be-transmitted packet, so as to transmit the to-be-transmitted packet based on the target path, where a congestion degree of the target path is less than a congestion degree of the current path, each entry of the path congestion information table includes a transmission path and congestion information corresponding to the transmission path, and the congestion information is used to indicate a congestion degree of the transmission path.