A data sending method includes receiving, by a forwarding device using a first flexible Ethernet (FlexE) group and in multiple timeslots included in a first timeslot set, multiple first encoded data blocks from a physical coding sublayer (PCS), determining, by the forwarding device according to the timeslots included in the first timeslot set and the first FlexE group, a second FlexE group and multiple timeslots included in a second timeslot set, and sending, by the forwarding device, the first encoded data blocks using the second FlexE group and in the timeslots included in the second timeslot set.