With the growing amount of existing structures, it becomes a more obvious problem for the maintenance management of existing structures. However, in the engineering practice, integration of information for existing structures is a tricky problem in the maintenance management. By using the BIM technology and IFC standard, a practical way to integrate appraisal and strengthening information for existing structures is proposed. By means of extending property in IFC standard, the basic appraisal information in the levels of structural system and structural members can be integrated. And for the five common strengthening methods for reinforced concrete structural members, the strengthening information of members can also be integrated. The integrated information could be read by any piece of software that support IFC standard. Finally, a system for maintenance of existing structures is designed on the basis of the proposed model, and it has been validated to be applicable by a practical engineering practice.