QoS-aware applications have become urgently demanded especially in service oriented computing environment. Specifying software architectures of QoS-aware applications is not a trivial task because such architectures are complex and dynamic, evolving at runtime according to QoS values and changes. To specify architectures of QoS-aware applications requires to solve two problems i.e. how to specify QoS in the architectures and how to specify the dynamism of the architectures. The dynamism of the architectures can be modelled with primitive actions of Archware π-ADL. In this paper, through the definition of QoS enhanced architecture styles, π-ADL is extended with QoS specifications to facilitate the architecture modelling of QoS-aware applications, in which QoS specifications are handled as first class entities. The QoS-based architectural mismatch check is developed to detect some QoS violations at the stage of architecture design. A case study is given to illustrate how to describe QoS-aware architectures and how to do the QoS-based architectural mismatch check.