Abstract: The primary combination of remote sensing (RS) with geographic information system (GlS) is mainly realized by the transforms of data structure. Because of its own limitations, it is in urgent need to investigate the integration of RS with GIS in higher levels. In this paper, the different types of combinations between RS and GIS are discussed, and that GIS data should be directly brought into image processing from the first is proposed. A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described. The example for the determination of granularity of spatial data processing relating to run-length-code line is also given.