A method for controlling access to a shared network, characterised in that the method comprises: receiving, by an access network node, an overload indicator capable of distinguishing multiple Public Land Mobile Networks, PLMN, wherein a core network node shared by the multiple PLMNs has different load thresholds predefined according to the multiple PLMNs, respectively; when overload of the core network node in the shared network has occurred, a PLMN over which access control needs to be performed is determined according to an overload status of the core network node, by judging which of the multiple PLMNs causes the overload of the core network node or load of which of the multiple PLMNs exceeds a predefined load threshold; the overload indicator carries an identifier of the PLMN over which access control needs to be performed, an access control type, and a waiting time length; and learning, by the access network node, the PLMN over which access control needs to be performed according to the identifier in the overload indicator received, wherein the receiving, by an access network node, an overload indicator capable of distinguishing multiple Public Land Mobile Networks, PLMN, comprises: receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs directly from the core network node, when the core network node is overloaded; or receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs via an operation and maintenance system, when the core network node is overloaded. receiving, by an access network node, an overload indicator capable of distinguishing multiple Public Land Mobile Networks, PLMN, wherein a core network node shared by the multiple PLMNs has different load thresholds predefined according to the multiple PLMNs, respectively; when overload of the core network node in the shared network has occurred, a PLMN over which access control needs to be performed is determined according to an overload status of the core network node, by judging which of the multiple PLMNs causes the overload of the core network node or load of which of the multiple PLMNs exceeds a predefined load threshold; the overload indicator carries an identifier of the PLMN over which access control needs to be performed, an access control type, and a waiting time length; and learning, by the access network node, the PLMN over which access control needs to be performed according to the identifier in the overload indicator received, wherein the receiving, by an access network node, an overload indicator capable of distinguishing multiple Public Land Mobile Networks, PLMN, comprises: receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs directly from the core network node, when the core network node is overloaded; or receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs via an operation and maintenance system, when the core network node is overloaded. receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs directly from the core network node, when the core network node is overloaded; or receiving, by the access network node, the overload indicator capable of distinguishing the multiple PLMNs via an operation and maintenance system, when the core network node is overloaded.