A load balancing method performed by a source end, comprising: determining, based on load statuses of respective probe channels on n paths between the source end and a destination end, a target path with a lightest load in the n paths, wherein for each of the n paths transmission channels between the source end and the destination end are classified into a data channel used to transmit a data packet and a probe channel used to transmit a probe packet that comprises a bandwidth probe packet, wherein a data packet rate on the data channel is adjusted based on a packet loss rate of a bandwidth probe packet limited by the probe channel, wherein the bandwidth probe packet is used to probe an available bandwidth, and wherein n is an integer greater than 1; sending a bandwidth probe packet to the destination end through a probe channel on the target path, and receiving the bandwidth probe packet returned by the destination end; and sending, based on the bandwidth probe packet returned by the destination end, a to-be-transmitted data packet to the destination end through a data channel on the target path; wherein the probe packet further comprises a load probe packet; and before the determining, based on load statuses of respective probe channels on n paths between a source end and a destination end, a target path with a lightest load in the n paths, the method further comprises: sending a load probe packet to the destination end through a probe channel on each of the n paths, and receiving the load probe packet returned by the destination end; and determining, based on the load probe packet returned on each path, a load status of the probe channel on each path, and wherein the load status of the probe channel on each path reflects a load status of the data channel on each path. determining, based on load statuses of respective probe channels on n paths between the source end and a destination end, a target path with a lightest load in the n paths, wherein for each of the n paths transmission channels between the source end and the destination end are classified into a data channel used to transmit a data packet and a probe channel used to transmit a probe packet that comprises a bandwidth probe packet, wherein a data packet rate on the data channel is adjusted based on a packet loss rate of a bandwidth probe packet limited by the probe channel, wherein the bandwidth probe packet is used to probe an available bandwidth, and wherein n is an integer greater than 1; sending a bandwidth probe packet to the destination end through a probe channel on the target path, and receiving the bandwidth probe packet returned by the destination end; and sending, based on the bandwidth probe packet returned by the destination end, a to-be-transmitted data packet to the destination end through a data channel on the target path; wherein the probe packet further comprises a load probe packet; and before the determining, based on load statuses of respective probe channels on n paths between a source end and a destination end, a target path with a lightest load in the n paths, the method further comprises: sending a load probe packet to the destination end through a probe channel on each of the n paths, and receiving the load probe packet returned by the destination end; and determining, based on the load probe packet returned on each path, a load status of the probe channel on each path, and wherein the load status of the probe channel on each path reflects a load status of the data channel on each path. sending a load probe packet to the destination end through a probe channel on each of the n paths, and receiving the load probe packet returned by the destination end; and determining, based on the load probe packet returned on each path, a load status of the probe channel on each path, and wherein the load status of the probe channel on each path reflects a load status of the data channel on each path.