The construction of schools has a long history in Iran. But with the evolution of Islamic civilization and the development of literature and other sciences, it was not possible to be content with the circles of mosques where scattered debates took place. Therefore, the establishment of certain centers for this purpose seemed necessary. An institution in which higher education and traditional Islamic sciences such as hadith, commentary, jurisprudence and the like are established. Among the Islamic nations, the first people to feel this need were the Iranians, who for some time built simple, uninhabited schools, libraries, and the like, and then fully equipped schools such as the military. The city of Isfahan is one of the centers of Iranian architecture, which is known as Dar-ul-Alam Shargh, and the construction of religious schools next to its mosques began during the Al-Buwayh and Al-Ziyar periods. But over time, some of them have been lost or their faces have changed and no written information about the condition of their spaces is available. Previous studies on schools can be divided into several areas. Part of it is physical and functional analysis, other categories are typology and in the last part, studies have a historical aspect. According to studies, less research can be observed in the field of historical schools that has divided the functional structure of school spaces. Therefore, in this article, for the first time, by analyzing the functional characteristics, the historical schools of Isfahan have been analyzed. Leading research seeks to answer these questions: What are the most significant criteria in the plan of historical schools in Isfahan, which are included in the functional structure of their plan? And how can these criteria be examined in the micro-spaces of these schools? By answering these questions, one can recognize a part of the architectural identity of historical schools in Isfahan and reveal many meaningful repetitive principles and concepts in these uses. This research is fundamental in terms of what is qualitative and based on purpose. It also studies the samples with an analytical-descriptive approach. The present study is non-experimental in terms of data collection and retrospective in terms of time element. To achieve the objectives of this research, data collection has been obtained through library studies and field methods (plan capture, etc.). The tools used include manual meters and laser meters, as well as video documentation tools including photography. The statistical population of this study includes more mosque-schools (Rahim Khan, Sayyid, Rokna Al-Molk and Hakim) and some mosques such as Abbasi Mosque and Jame Mosque, which have Sulaimaniyah, Nasiri and Mozaffariyeh schools next to them, respectively. Of 23 pieces. Now, in order to provide a suitable measurement for the analysis, the seven mentioned samples have been removed from the statistical population. The samples are purposefully selected and correspond to the eighth to fourteenth centuries AH and their number is 16. The samples in this study are analyzed based on the five criteria mentioned and based on each criterion, different plan structures are presented in the form of tables. Data collection is based on authors' library and field studies. During this research, the criteria of the structural index of the plan of historical schools in Isfahan have been determined. These five index criteria that identify the commonalities and differences in the samples include, spatial diversity (outdoor, semi-open and closed), uses in schools and functions of different parts of the building (educational, Residential, prayer, cultural), building circulation (entrance device circulation, access to cells, access to prayer space in schools with prayer space and domes and movement circulation in the corners of the central courtyard), location and form of the device Stairs include, joining and enclosing the building and finally the type of space system (central-axial). These five criteria have created a different functional and spatial structure in the school plans of this city. These five criteria can be examined in different sections in such a way that in the analysis of spatial diversity, most of the samples have various open and semi-open spaces (in terms of multiplicity) that are formed with the center of the central courtyard. Also, the study of the place of prayer space in schools has placed them in three general categories. On the other hand, he pointed out that in schools attributed to the Safavid period onwards, the use of prayer has a special space, which before this use was shared with other uses in school spaces. Analyzes of the circulation criterion revealed that differences could be observed in different areas and sections of schools. On the other hand, access to the upper floors in the samples is done only with a stair device enclosed in the building. The stairwell is usually located next to the porches. This research can also provide an approach for other researchers to study buildings with similar uses, such as caravanserais.