Increasing application of Geospatial information requires integration

fusion and interoperability of current monolithic GIS

especially of more complex and multidisciplinary application. Interoperability is the base for information integration and fusion. A five level GIS interoperability model is given. The spatial information infrastructure (SII) provides a sharing spatial information framework

architecture and an interoperability platform for geographical information system. This paper studies architecture of spatial information infrastructure

and gives the relationship between GIS interoperability model and spatial information infrastructure architecture. We consider GIS interoperability model provides theory base for SII

and SII provides an implementation platform for GIS interoperability model.