A method, network element, and mobile station (MS) are disclosed. The method includes: obtaining information that a plug-in card of the MS does not support a first encryption algorithm; deleting the first encryption algorithm from an encryption algorithm list permitted by a core network element according to the information that the plug-in card of the MS does not support the first encryption algorithm; sending the encryption algorithm list excluding the first encryption algorithm to an access network element, so that the access network element selects an encryption algorithm according to the encryption algorithm list excluding the first encryption algorithm and the MS capability information sent from the MS and sends the selected encryption algorithm to the MS. By using the method, network element, and MS, errors due to the fact that the plug-in card of the MS does not support an encryption algorithm may be avoided during the encryption process.