Abstract: As the blueprint for software development, software architecture(SA) is very important, and much more attention has been paid to the research on SA. Through analyzing current architecture description methods(ADM), this paper point out their shortcoming and presents an XML and component operations based ADM-XCOBA. It applies XML to the description of SA, and possesses many advance characteristics. Through describing the basic elements of SA and make use of component operations describe SA,XCOBA has the ability of describing the high level structure of software system. Because of the characteristics of XML, XCOBA supports refinement and evolution, which can be carry out the communication between the different component, and SA has an advanced extensibility in this describe method.