Unified geo-reference data model is a very important part of national geographic information management. It has been developed within the project of Lithuanian geographic information infrastructure in 2006-2008. This model allows automated integration of large scale (mainly municipality) geo-reference data into the unified national geo-reference database. It is based on unique object identifiers across all geo-reference databases and on standard update and harmonisation procedures. The common stages of harmonisation of geo-reference databases at different scales include: implementation of a unique identifier of geographic objects across all databases concerned; definition of the life cycle of the objects; definition of cohesion boundary and of the harmonisation points along the boundary; maintenance of the local database and automatic update of the national database using special service. When implemented, such model will significantly facilitate maintenance of national geo-reference database and in five years from full implementation will have a significant economic effect. PUBLICATION ABSTRACT