In this article, we will examine the structure and function of Brecht's epic theater, taking into account the social, political, and artistic contexts, schools of thought, and the diachronic process; we will also examine its key terms, including dialectics, alienation, historicization, and social gestus, in the works of this period. In this article, which employs a descriptive and analytical method, we will answer the fundamental question of what distinguishes epic theater from realistic theater by using library and internet resources and a comparative analysis of the views and theories of Friedrich Hegel and Karl Marx with Bertolt Brecht. Then we will examine the extent of their influence and the application of some of their theories in the context of Brecht's plays, especially his post-exile works. Next, we will redefine some terms with reference to Eugenio Barba's performance theories, Gadamer's philosophy, and Walter Benjamin, the commentator on Brecht's works and his contemporary. This article aims to redefine epic theater based on Brecht's theories and plays from his mature period. Based on this hypothesis, the set of techniques employed under the term "alienation" in the works of this period differs significantly from Brecht's earlier works. Alienation in educational dramas is done to educate workers, but in Brecht's dramatic plays, these techniques are implicitly used in the text. The conclusion drawn from this research indicates that not only does the translation of the theater of which Brecht was the main theorist into epic seem incorrect, but also that addressing epic theatre solely from an aesthetic perspective, without considering the political-social context, Brecht’s schools of thought, and the diachronic process, has led to misunderstandings and misinterpretations of his works.