Module and proportions are substantially important in architecture, however: the studies of them do not meet one’s expectations in Iranian architecture. This issue is more noteworthy in Iran’s historical architecture. Median era is one of the most significantly important periods in Iran that caused new architectural designs and techniques to flourish. Nevertheless, few surveys have been conducted on the Module and proportions of this era which results in many ambiguities in this case. This paper attempts to discover the median modules and proportions. The well reserved architecture of Nushijan among other Median sites makes it a proper case for this research and it is also a suitable reference for comparing other Median sites. After conducting the field study, measuring the dimensions precisely and studying the excavation reports and evidences, the measurements were studied by AutoCAD and Matlab. Then the result was checked through statistical analysis. The results show a specific relation between the ratios of the length and the width of different structures. For instance the ratio of Nushijan length and width are similar to the ratio of Tell-Quba which is 5.02 on average. In addition, it seems that the median architecture followed a certain module of 20 cm which is observed in the construction of other buildings in Nushijan (castle, central and old western temple). Module and proportions are substantially important in architecture, however: the studies of them do not meet one’s expectations in Iranian architecture. This issue is more noteworthy in Iran’s historical architecture. Median era is one of the most significantly important periods in Iran that caused new architectural designs and techniques to flourish. Nevertheless, few surveys have been conducted on the Module and proportions of this era which results in many ambiguities in this case. This paper attempts to discover the median modules and proportions. The well reserved architecture of Nushijan among other Median sites makes it a proper case for this research and it is also a suitable reference for comparing other Median sites. After conducting the field study, measuring the dimensions precisely and studying the excavation reports and evidences, the measurements were studied by AutoCAD and Matlab. Then the result was checked through statistical analysis. The results show a specific relation between the ratios of the length and the width of different structures. For instance the ratio of Nushijan length and width are similar to the ratio of Tell-Quba which is 5.02 on average. In addition, it seems that the median architecture followed a certain module of 20 cm which is observed in the construction of other buildings in Nushijan (castle, central and old western temple). Module and proportions are substantially important in architecture, however: the studies of them do not meet one’s expectations in Iranian architecture. This issue is more noteworthy in Iran’s historical architecture. Median era is one of the most significantly important periods in Iran that caused new architectural designs and techniques to flourish. Nevertheless, few surveys have been conducted on the Module and proportions of this era which results in many ambiguities in this case. This paper attempts to discover the median modules and proportions.