The process of enterprise architecture (EA) is divided into strategic IT planning, EA development and EA implementation phases, respectively. Each phase is a prerequisite to the following phase. If the enterprise architecture planning (EAP) is not properly formulated during this process, its implementation would face problems and consequently a large amount of time and money would be wasted. EAP should be redefined to solve this issue. Definition of a method for the evaluation of EAP before the implementation of EA can be very useful in avoiding money and time loss caused by inappropriate EAP. A variety of methods are proposed around the world for evaluating EA but none of them can define and evaluate it in enterprises with uncertain processes or data. This research aims to present a new method for evaluating the reliability of EA while processes or data are uncertain. To achieve this goal, the products of fuzzy enterprise architecture (FEA) which demonstrate the behavior and sequence of processes and details of the enterprise are converted into fuzzy Petri nets. Afterwards, reliability evaluation is performed with fuzzy Petri nets which are executable models. In this method, uncertain processes and events can be easily modeled and evaluated. Therefore, the model proposed in this research is considered as a new method in EA. This method is executable and can be used in EA three-stage process.