Validation of software systems is very useful at the primary stages of their development cycle. Evaluation of functional requirements is supported by clear and appropriate approaches, but there is no similar strategy for evaluation of non-functional requirements (such as performance and reliability). Whereas establishing the non-functional requirements have significant effect on success of software systems, therefore considerable necessities are needed for evaluation of non-functional requirements. Also, if the software performance has been specified based on performance models, may be evaluated at the primary stages of software development cycle. Therefore, modeling and evaluation of non-functional requirements in software architecture level, that are designed at the primary stages of software systems development cycle and prior to implementation, will be very effective. We propose an approach for evaluate the performance and reliability of software systems, based on formal models (hierarchical timed colored petri nets) in software architecture level. In this approach, the software architecture is described by UML use case, activity and component diagrams, then UML model is transformed to an executable model based on hierarchical timed colored petri nets (HTCPN) by a proposed algorithm. Consequently, upon execution of an executive model and analysis of its results, non-functional requirements including performance (such as response time) and reliability may be evaluated in software architecture level.