Criterions of open geospatial consortium(OGC) for spatial data service only support interoperability of the syntax level and can not solve problems of semantic heterogeneity.This paper proposes a novel ontological query scheme of spatial data service.It builds renewable ontology library based on ontology theory

and defines the calculation model of semantic similarity as the core of ontology-based retrieval model for spatial data services

which effectively deals with a large number of historical data stored in database or OGC services.Experimental test results show that the new approach is effective.