Software reliability modeling, as a non-functional characteristic of software quality to achieve high reliability, is of particular importance. To obtain software systems with high reliability, it is important to select the best scenario, from the various scenarios produced, in a short time during the software design stage. Since the scenario includes interactions between the user and use case, producing various scenarios and selecting the best among them in terms of reliability is a difficult and time-consuming task for software designers. Therefore, it is of great importance to use a modeling language that has a tool-based evaluation modeling approach and does the analysis automatically. In this paper, Alloy modeling language has been used to model and analyze software reliability. Compared to other lightweight modeling languages, Alloy has such advantages as being more concise, accurate and abstract. The primary objective of this paper aims to present a modeling framework based on the Alloy modeling language with which reliability of target systems can be efficiently examined. The results indicate that the use of Alloy analyzer facilitates the immediate production of various scenarios and allows for the selection of the best one in terms of reliability.