A data sending method, wherein the method is applied to a base station device and comprises: receiving an uplink data packet sent by user equipment UE; and characterised in that: if a signaling message is carried in the uplink data packet, separating the signaling message from the uplink data packet, wherein the signaling message is used to request to establish a packet data unit PDU session or request to activate an established PDU session; forwarding the signaling message to a control plane device, so that the control plane device establishes the PDU session or activates the established PDU session; and before an available PDU session exists, forwarding, based on a data forwarding message carried in the uplink data packet sent by the UE, data in the uplink data packet sent by the UE, wherein the data forwarding message comprises information required when a data packet is forwarded in a sessionless manner; wherein the forwarding, based on the data forwarding message carried in the uplink data packet sent by the UE, data in the uplink data packet sent by the UE comprises: determining whether the data forwarding message comprises path information of the uplink data packet; if the data forwarding message comprises the path information, determining a shared link between the base station device and a target user plane network element UPF based on a quality of service QoS class identifier comprised in the data forwarding message, wherein the target UPF is a UPF indicated in the path information; and forwarding the data in the uplink data packet to the target UPF over the shared link; and if the data forwarding message does not comprise the path information, selecting a target routing table based on network slice selection assistance information NSSAI comprised in the data forwarding message; searching the target routing table based on an Internet protocol IP address that is of a communications peer end and that is carried in the uplink data packet, to obtain a target UPF; determining a shared link between the base station device and the target UPF based on a QoS class identifier comprised in the data forwarding message; and forwarding the data in the uplink data packet to the target UPF over the shared link. if a signaling message is carried in the uplink data packet, separating the signaling message from the uplink data packet, wherein the signaling message is used to request to establish a packet data unit PDU session or request to activate an established PDU session; forwarding the signaling message to a control plane device, so that the control plane device establishes the PDU session or activates the established PDU session; and before an available PDU session exists, forwarding, based on a data forwarding message carried in the uplink data packet sent by the UE, data in the uplink data packet sent by the UE, wherein the data forwarding message comprises information required when a data packet is forwarded in a sessionless manner; wherein the forwarding, based on the data forwarding message carried in the uplink data packet sent by the UE, data in the uplink data packet sent by the UE comprises: determining whether the data forwarding message comprises path information of the uplink data packet; if the data forwarding message comprises the path information, determining a shared link between the base station device and a target user plane network element UPF based on a quality of service QoS class identifier comprised in the data forwarding message, wherein the target UPF is a UPF indicated in the path information; and forwarding the data in the uplink data packet to the target UPF over the shared link; and if the data forwarding message does not comprise the path information, selecting a target routing table based on network slice selection assistance information NSSAI comprised in the data forwarding message; searching the target routing table based on an Internet protocol IP address that is of a communications peer end and that is carried in the uplink data packet, to obtain a target UPF; determining a shared link between the base station device and the target UPF based on a QoS class identifier comprised in the data forwarding message; and forwarding the data in the uplink data packet to the target UPF over the shared link. determining whether the data forwarding message comprises path information of the uplink data packet; if the data forwarding message comprises the path information, determining a shared link between the base station device and a target user plane network element UPF based on a quality of service QoS class identifier comprised in the data forwarding message, wherein the target UPF is a UPF indicated in the path information; and forwarding the data in the uplink data packet to the target UPF over the shared link; and if the data forwarding message does not comprise the path information, selecting a target routing table based on network slice selection assistance information NSSAI comprised in the data forwarding message; searching the target routing table based on an Internet protocol IP address that is of a communications peer end and that is carried in the uplink data packet, to obtain a target UPF; determining a shared link between the base station device and the target UPF based on a QoS class identifier comprised in the data forwarding message; and forwarding the data in the uplink data packet to the target UPF over the shared link.