In this paper, we propose a temporal-based aythorization model for Group-centric Secure Information Sharing(g-SIS) . The traditional approach to information sharing focuses on attaching attributes and policies to an object as it is disseminated from producer to consumers in a system. In contrast, group-centric sharing brings subjects and objects together in a group to facilitate sharing. In such contexts, authorizations are influenced by the temporal ordering of subject and object group membership. That is, the authorizations are decided by the time that subject joins group and the time that object is added to group. But, the model doesn’t consider the time constraint of group enabling and access enabling. For example, a secure meeting room is open only at 8:00—10:00 am and 15:00—17:00 pm every Monday. We develop a temporal-based authorization model for group-centric information sharing which takes the temporal intervals of group and access enabling into consideration. We also discuss a usage scenario to illustrate practical application in secure meeting system.