Token updating method and device

The invention discloses a token updating method and device, and the method comprises the steps that a client side sends an access request to an application system, the access request carries a token pre-stored by the client side, and the token is issued by an authentication center; the authentication center intercepts the access request and judges whether the token carried in the access request is about to expire, and when the time difference between the effective deadline of the token and the current time is smaller than the preset duration, it is represented that the token is about to expire; under the condition that the authentication center determines that the token is about to expire, the token is updated, and the updated token is issued to the client; and the client replaces a pre-stored token with the updated token. As the authentication center can update the token before the token expires and return the updated token to the client, the token can be ensured to be always effective in the process of acce