This application discloses a flexible Ethernet group establishment method and a device. The method includes: determining that there are at least M physical layer PHY links; receiving at least M delay test requests sent by a near-end device; determining, by the far-end device, at least M receiving time points at which the at least M delay test requests are received; and determining M PHY links used to establish a flexible Ethernet group, from the at least M PHY links based on the at least M receiving time points, where a delay difference between any two of the M PHY links satisfies a preset delay condition. According to the method in this application, the delay difference between the any two PHY links is accurately determined based on time points at which delay test requests are received over any two PHY links.