A session establishment method performed by a control device, comprising: receiving first request information, wherein the first request information is used to indicate that a first terminal device requests to access a group communication service; determining a first terminal device group to which the first terminal device belongs; determining a target forwarding device that serves the first terminal device group, wherein the target forwarding device is a forwarding device capable of supporting a group communication service; and controlling the first terminal device to establish a session with the target forwarding device; wherein - terminal devices in the same first terminal device group establish sessions with the forwarding device, whereby group service access between the terminal devices in the first terminal device group is completed by using the same forwarding device without data exchange of the group communication service by a server, and - the forwarding device is configured: to probe a packet to determine one terminal device of the first terminal device group to which the packet is to be sent; or to determine a forwarding policy based on whether a packet belongs to the group communication service, and send the packet to one terminal device of the first terminal device group when the packet belongs to the group communication service. receiving first request information, wherein the first request information is used to indicate that a first terminal device requests to access a group communication service; determining a first terminal device group to which the first terminal device belongs; determining a target forwarding device that serves the first terminal device group, wherein the target forwarding device is a forwarding device capable of supporting a group communication service; and controlling the first terminal device to establish a session with the target forwarding device; wherein - terminal devices in the same first terminal device group establish sessions with the forwarding device, whereby group service access between the terminal devices in the first terminal device group is completed by using the same forwarding device without data exchange of the group communication service by a server, and - the forwarding device is configured: to probe a packet to determine one terminal device of the first terminal device group to which the packet is to be sent; or to determine a forwarding policy based on whether a packet belongs to the group communication service, and send the packet to one terminal device of the first terminal device group when the packet belongs to the group communication service. - terminal devices in the same first terminal device group establish sessions with the forwarding device, whereby group service access between the terminal devices in the first terminal device group is completed by using the same forwarding device without data exchange of the group communication service by a server, and - the forwarding device is configured: to probe a packet to determine one terminal device of the first terminal device group to which the packet is to be sent; or to determine a forwarding policy based on whether a packet belongs to the group communication service, and send the packet to one terminal device of the first terminal device group when the packet belongs to the group communication service.