One of the most important issues in GIS is Data interoperability. Emerging of web service technologies and SOA paradigm encouraged the evolution from Classical and data-centric GIS to distributed and loosely coupled architecture. With the increasing amount of users requesting spatial data, organizations published their spatial web services according to Existing standards(OGC,ISO). At the other hand, many organizations are providing similar services with overlapping functionalities. So there would be more web services to response for each request in UDDI. Selection of the best web service to response is a challenge. Web services have functionality and non-functionality aspect that they’re may be similar in functionality aspects but they’re different in non-functionality aspects (quality of service). Web service selection by QoS can be a good solution for this challenge that it can introduce the suitable web service to users. In this paper, we will describe QoS, Web service Level Agreement (WSLA) Standards for representing quality of web services and represent a model for spatial web services quality. Finally we will investigate QoS-Driven service selection methods for web service composition.