A clock synchronization packet exchanging method includes sending, by a first device in a Flexible Ethernet (FlexE) group, a first FlexE instance at a first physical layer (PHY), where the first FlexE instance includes a clock synchronization packet, and a second FlexE instance sent by the first device in the FlexE group at a second PHY also includes a clock synchronization packet. The clock synchronization packets are carried in a plurality of FlexE instances transmitted between a transmit end and a receive end in the FlexE group.