Abstract: In order to realize the core functions of incar navigation system,a function based navigation data model is put forward,in which the whole organization principles and organization model of navigation data are addressed.In the whole organization principles,firstly,different scales data are classified into different levels in vertical direction and divided into blocks in horizontal direction.Then the data are organized into map display related levels,route planning related levels and POI related levels.In the data organization model,road data mode is researched in detail,in which map display related model and route planning related model are discussed,as well their supporting to core functions of navigation system.Experiment results demonstrate the data model described is able to synthetically realize the core functions of navigation system in an effect and convenience way,which is fit for navigation system.