A connection establishment method, comprising: receiving, by a central unit, CU, function entity, a first connection establishment request of a master device, wherein the first connection establishment request comprises at least first identification information of a terminal, identification information of a first data radio bearer DRB, identification information of a target cell, and interface information of the master device, wherein the CU function entity includes a Radio Resource Control, RRC and a Packet Data Convergence Protocol, PDCP; sending, by the CU function entity, a second connection establishment request to a distributed unit, DU, function entity, wherein the second connection establishment request comprises at least second identification information of the terminal, the identification information of the first DRB, and the interface information of the master device, and the DU function entity is associated with the target cell, wherein the DU function entity includes a Radio Link Control, RLC, a Medium Access Control, MAC, and a Physical Layer, PHY; receiving, by the CU function entity, a first response message of the DU function entity, wherein the first response message comprises at least the identification information of the first DRB and interface information of the DU function entity; and sending, by the CU function entity, a second response message to the master device, wherein the second response message comprises at least the identification information of the first DRB and the interface information of the DU function entity, wherein the interface information of the master device comprises at least an interface identifier and an interface transmission address of the master device, wherein the interface information of the DU function entity comprises at least an interface identifier and an interface transmission address of the DU function entity. receiving, by a central unit, CU, function entity, a first connection establishment request of a master device, wherein the first connection establishment request comprises at least first identification information of a terminal, identification information of a first data radio bearer DRB, identification information of a target cell, and interface information of the master device, wherein the CU function entity includes a Radio Resource Control, RRC and a Packet Data Convergence Protocol, PDCP; sending, by the CU function entity, a second connection establishment request to a distributed unit, DU, function entity, wherein the second connection establishment request comprises at least second identification information of the terminal, the identification information of the first DRB, and the interface information of the master device, and the DU function entity is associated with the target cell, wherein the DU function entity includes a Radio Link Control, RLC, a Medium Access Control, MAC, and a Physical Layer, PHY; receiving, by the CU function entity, a first response message of the DU function entity, wherein the first response message comprises at least the identification information of the first DRB and interface information of the DU function entity; and sending, by the CU function entity, a second response message to the master device, wherein the second response message comprises at least the identification information of the first DRB and the interface information of the DU function entity, wherein the interface information of the master device comprises at least an interface identifier and an interface transmission address of the master device, wherein the interface information of the DU function entity comprises at least an interface identifier and an interface transmission address of the DU function entity.