A data transmission method includes detecting a delay between a source end and a sink end; determining a to-be-used second path when a first path currently used to transmit a packet is determined to be a congested path; determining a delay difference between the first path and the second path based on a delay of the first path and a delay of the second path; and sending one or more to-be-sent packets to the sink end through the second path based on the delay difference.