With the spread of the Internet and software evolution in complex intensive systems, software architecture often need be reconfigured during runtime to adapt variable environ-ments and design objectives. To deal with reconfigurable software architectures, the formal method should be pre-sented to describe software architectures and express their changes so that these changes on the evolutions of software architectures could be reasoned about. However, current formal methods for reconfigurable software architectures are difficult to represent hierarchy and model context-aware systems. In this paper, we use and extend Bigraph as a formal method to describe reconfigurable software archi-tecture. By providing graphic elements and term languages, extended bigraphs can survey static and dynamic architec-tures easily. Then we represent basic architectural opera-tions based on extended bigraphs, through a case describe reconfigurations with constraints and context-aware infor-mation by reaction rules, and illustrate how to check the properties to satisfy design requirements by BiLog.