A load balancing method, device and system, where the method includes: 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, where a probe channel is used to transmit a probe packet that includes a bandwidth probe packet; sending a bandwidth probe packet to the destination end through a probe channel on the target path; 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. Therefore, load balancing among a plurality of paths is implemented.