Growing attention has been paid to access control in information system, especially the access control of resource access requires in office automation area. However, traditional role-based access control model and task-based access control model cannot satisfy the workflow changeable requirements. To solve these problems, the task-role-based access control mode is introduced, which can satisfy the requirements of authority managements from business fields related to office automation. At the end of the paper, combined with the practical development of office automation system, the detailed implementation instance of task-role-based access control mode is provided.