Introduction: Two important encyclopedias have been written in the era of scientific flourishing in Islam world, first “Iḥṣā al-ulūm” (the census of Knowledge) written by “Abu Nasr Al-Farabi”, and second, “Māfatih Al-Olum” (Keys to sciences) written by “Abd-Allāh Kāteb Kārazmi”. Both scientists are Khorasani and both of these encyclopedias have payed attention to crafts and practical sciences under the name of “Science of Hiall”. Based on existing evidence, the Iranian specially Khorasani scientists have had an important role in the production and recording these sciences but unfortunately, the nature of these sciences and the role of Iranians in the production of them have not been considered properly, yet.Given the importance of this issue, the primary question of this research was: “Where is the place of design and creative thinking in the classification of Islamic sciences, in particular, in the encyclopedia of Iḥṣā al-ulūm? According to the preliminary study, this research focused on the "Science of Hiall” branch, in the "Educational Sciences" group. After documentary information gathering, the definitions presented by Farabi, the explanatory texts of Hiall, and the existing designs were revised. Then, focused on the two factors, creative thinking and design methodology, the logical patterns and design methods of existing designs have been analyzed. Based on these analyses, seven sets of discussion are presented in this paper. According to these arguments, the design method used in producing the devices in science of Hiall is based on creative thinking pattern, not based on the deductive model or the Mathematics Calculation.