A data transmission link establishment apparatus, wherein the data link establishment apparatus is disposed on or is a host node, the data link establishment apparatus comprising: a selection unit, configured to select a target node; wherein the selection unit comprises: a capability detection subunit, configured to detect a data backhaul capability between each access node and the host node; and an access node selection subunit, configured to select, according to a detection result of the capability detection subunit, an access node with an inadequate data backhaul capability as the target node; a determining unit, configured to determine a backhaul node that needs to establish a data transmission link with the target node selected by the selection unit, and configured to select an access node as the backhaul node, wherein the access node has an idle data transmission resource and can establish, by using an air interface, a connection with the target node selected by the selection unit; a setting unit, configured to set protocol stack roles, in the data transmission link, of the target node and the backhaul node that is determined by the determining unit; and a configuration unit, configured to configure the target node and the backhaul node according to the protocol stack roles that are set by the setting unit for establishing the data transmission link between the target node and the backhaul node; wherein both the target node and the backhaul node have at least two protocol stacks; and wherein the setting unit comprises: a direction determining subunit, configured to determine a data transmission direction between the target node and the backhaul node; a channel selection subunit, configured to select a channel used for data transmission between the target node and the backhaul node; and a role setting subunit, configured to determine the protocol stack roles of the target node and the backhaul node according to the data transmission direction determined by the direction determining subunit and the channel selected by the channel selection subunit. a selection unit, configured to select a target node; wherein the selection unit comprises: a capability detection subunit, configured to detect a data backhaul capability between each access node and the host node; and an access node selection subunit, configured to select, according to a detection result of the capability detection subunit, an access node with an inadequate data backhaul capability as the target node; a determining unit, configured to determine a backhaul node that needs to establish a data transmission link with the target node selected by the selection unit, and configured to select an access node as the backhaul node, wherein the access node has an idle data transmission resource and can establish, by using an air interface, a connection with the target node selected by the selection unit; a setting unit, configured to set protocol stack roles, in the data transmission link, of the target node and the backhaul node that is determined by the determining unit; and a configuration unit, configured to configure the target node and the backhaul node according to the protocol stack roles that are set by the setting unit for establishing the data transmission link between the target node and the backhaul node; wherein both the target node and the backhaul node have at least two protocol stacks; and wherein the setting unit comprises: a direction determining subunit, configured to determine a data transmission direction between the target node and the backhaul node; a channel selection subunit, configured to select a channel used for data transmission between the target node and the backhaul node; and a role setting subunit, configured to determine the protocol stack roles of the target node and the backhaul node according to the data transmission direction determined by the direction determining subunit and the channel selected by the channel selection subunit. a direction determining subunit, configured to determine a data transmission direction between the target node and the backhaul node; a channel selection subunit, configured to select a channel used for data transmission between the target node and the backhaul node; and a role setting subunit, configured to determine the protocol stack roles of the target node and the backhaul node according to the data transmission direction determined by the direction determining subunit and the channel selected by the channel selection subunit.