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). 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 of software systems, based on black board technique in software architecture level. In this approach, at first, software architecture using blackboard technique is described by UML use case, activity and component diagrams. then UML model is transformed to an executable model based on timed colored petri nets(TCPN) Consequently, upon execution of an executive model and analysis of its results, non-functional requirements including performance (such as response time) may be evaluated in software architecture level.