A multi-band transmission method implemented by a receive end, where the method includes: receiving data packets in parallel from a transmit end using M frequency bands, where the data packets belong to a same traffic stream; receiving a BAR from the transmit end, where the BAR carries an SSN and requests a receiving state of a data packet from the transmit end on the mth frequency band; marking an mth state for an unreceived data packet whose SN is before the SSN; marking one or more unreceived data packets with a discarded state when determining the one or more unreceived data packets are marked with a first state, a second state, . . . , and an Mth state; determining whether there are data packets with consecutive SNs; and if yes, submitting a data packet that is in the received state and in the data packets with the consecutive SNs.