A method for processing an access-request message in an IMT-2000 system is described. A user password is encrypted by a temporary authenticator value and an authenticator value which is able to verify an access-request message itself is generated, so that when an AAA server receives the access-request message, it can directly verify the access-request message without analyzing the received access-request message. Thus, even if a malicious hacker transmits a large quantity of false access-request message to the AAA server, the use of the system resource and the message processing time are reduced, so that the system is prevented from crashing.