The invention relates to an OA intelligent office system and a management method thereof. The system comprises a system function module responsible for the system code settlement, the role authorization management service and the message notification service, a working module responsible for the outgoing message management, the incoming massage management, the basic settlement, the to-be-done job settlement, the job inquiry, the process log, the overtime statistics and the project completion data filing, and a system management module responsible for the administrative office settlement, the information exchange settlement, the timed task management, the workflow settlement and the organization mechanism settlement. The working module acquires the usage authorization information, the login information and the message reminding of a user by means of the system function module. The system management module acquires the data of the system authorization management, the settlement data of the workflow, the settlement data of roles in the company of the above user and the settlement data of document templates by means of the system function module. The working module acquires the operating authorization of incoming massages and outgoing messages, the job inquiry authorization and the division basic data of project completion items by means of the system management module. According to the invention, the electronic signature technology, the project management service management and the OA office flow function are integrated.