Provided is a method for handling a packet data unit (PDU) session establishment procedure. The method may performed by an access and mobility management function (AMF) node and comprise: determining whether to reject a PDU session establishment request. The determination may be performed if the PDU session establishment request includes an existing PDU session identifier. Based on the existing PDU session identifier, an identifier of a session management function (SMF) node may be acquired. The PDU session establishment request may be accepted, if it is determined based the identifier of the SMF node that the SMF node and the AMF node belong to a same PLMN. The PDU session establishment request may be further accepted, if it is determined based the identifier of the SMF node that the SMF node belongs to a HPLMN. The PDU session establishment request may be rejected, if it is determined based the identifier of the SMF node that the SMF node and the AMF node do not belong to the same PLMN or the SMF node does not belong to the HPLMN.