Public administration business system can be classified as a hierarchical system where the development of suitable information system has to allow data collection, business processes integration, and knowledge distribution and usage. Public administration hierarchical structure enjoins data and information flow from the end user to the management in business plan and the realization domain, and in the reverse direction in the tasks distribution and related information domain. Each autonomous organizational structure (state, local and regional governments) should provide an unambiguous and transparent data management by defining criteria (called classification) carrying information. Business areas should interconnect within a single organization (horizontal integration), or among the entities in the hierarchy (vertical integration). The information system as a whole and its subsystems enable high quality knowledge creation and its application through knowledge management at all hierarchical levels. This paper emphasizes data, business processes modeling and design in the general conceptual knowledge model using ontology. A method to identify and design a model at the entity level, to compare these models and create a general model at public administration individual units level, and develop meta-level model on the number of independent units is presented. Ontology is an integral part of the domain process and data modeling at the meta-information level. Applying ontology enables the conceptual knowledge design and the use of formal knowledge. [ABSTRACT FROM PUBLISHER]