1. A method for implementing access restriction of mobile networks, comprising the steps of: a Mobile Station (MS) inquiring a list of forbidden Public Land Mobile Networks (PLMNs) and access technology identifiers, which is saved by the MS, when the MS selects a PLMN network; the MS determining whether the selected PLMN network and the access technology exist in the list of forbidden PLMNs and access technology identifiers, if they exist, the MS not sending a Location Updating Request to a Mobile Switching Center/Serving GPRS Support Node (MSC/SGSN) of a Core Network; otherwise, the MS sending the Location Updating Request to the MSC/SGSN in order to access to the network; modifying the content of the list of forbidden PLMNs and access technology identifiers, wherein the modifying comprises: if the MS successfully accesses a certain PLMN network through an access technology, the MS determining whether the PLMN number of the accessed network and corresponding access technology identifier exist in the list of forbidden PLMNs and access technology identifiers saved by the MS; if the PLMN number and the corresponding access technology identifier exist in the list, the MS deleting the access technology identifier corresponding to the PLMN number from the list.