Seals are important sources in the analysis of the history of each era. Methodological study of these works plays an important role in clarifying the political, social & economic issues of different historical periods. The motifs on the seals show the belief & attitude of the people of that time to the world around them. In addition to conveying aspects of visual beauty to the viewer, these motifs also convey the thoughts of its creators. Animal motifs have been more efficient & of great interest to Sassanid artists. Bull, as the fifth creature of Ohrmazd, from an economic, mythological & religious point of view, was the center of attention of Sassanid seal artists & owners. In this research, the authors, after taking a brief look at the role of the bull in the mythology & ancient texts of Iran, have examined it on Sassanid seals, & also introduced three inscribed seals with the motif of bulls from Bu- Ali Sina Museum which have been read by the authors of this article for the first time. At the end, the issue of possession & ownership of these seals & the concept of the inscriptions of the three seals have been examined. This article is prepared in a documentary method based on library studies & field research.