The present invention provides a service data transmission processing method and device and a communication system. The service data transmission processing method includes: receiving, by a service offloading apparatus, uplink service data sent by a user equipment; obtaining, by the service offloading apparatus, a service type of the uplink service data; and sending, by the service offloading apparatus, uplink service data, a service type of which is a core network service to a core network service proxy apparatus through a first service tunnel, or sending, by the service offloading apparatus, uplink service data, a service type of which is a non-core network service to a non-core network service proxy apparatus through a second service tunnel. The technical solutions can avoid excessive use of backhaul network resources of a core network by non-core network services.