A wireless communication system and an authentication method thereof are provided. The wireless communication system includes a User Equipment (UE), an Evolved Node B (eNodeB), a Home Subscriber Server (HSS), and a Mobility Management Entity (MME). Before the UE enters an Attachment Procedure, the MME is configured to acquire an Authentication Vector from the HSS in advance, and transmit, based on the Authentication Vector, a first Authentication Vector corresponding to the UE to the UE and a second Authentication Vector corresponding to the eNodeB to the eNodeB in advance. The eNodeB is configured to transmit a UE identifier to the UE. The UE is configured to complete an Authentication procedure with the eNodeB according to the UE identifier and the Authentication Vector.