Concerning the features of complex objects and massive data transmission, a new XML-based method to design and implement communication protocols for WebGIS is presented. With the aid of UML, the typical requiring and responding protocols of WebGIS are analyzed through object-oriented concept. Based on object oriented analysis of the protocols, the mechanism of designing communication protocols following W3Cs XML Schema specification is illustrated. Finally, the main flow of embedding the protocols into WebGIS is given by packing and parsing XML-based protocols in a WebGIS application prototype. This kind of protocols can be used in spatial information exchange among heterogeneous WebGIS platforms in distributed environment.