Cyber-physical systems (CPSs) are physical and engineered systems whose operations are monitored. Cyber-physical systems having quality-of-service (QoS) requirements driven by the dynamics of the physical environment in which they operate, the description, control, management, consultation and guarantee of QoS are very complex and challenging work, Quality of Service(QoS) is directly related to system's performance. This paper proposes an aspect-oriented QoS modeling method based on UML and formal methods. We use an aspect-oriented profile by the UML meta-model extension, and model the crosscutting concerns by this profile. In this paper, we build the aspect-oriented model for specifying Quality of Service (QoS) based on the combination of UML and RTL. We believe that the two types of notation, graphical (semi-formal) and, respectively, formal, can efficiently complement each other and provide the basis for an aspect-oriented specification approach that can be both rigorous and practical for QoS modeling. Two examples depict how aspect-oriented methods can be used during QoS analysis and design process