The subject of gypsum decoration has received attention from researchers who have been interested in creating huge encyclopedias about Islamic art throughout the ages, as gypsum decorations, in my opinion, reflect an important aspect of civilization and sophistication. They are considered a true mirror that reflects the artistic, social and political conditions of each era, any other type of art. I applied this to one of the mosques in Beheira Governorate and took it as a model for gypsum decorations in the Ottoman era, which is the Habashi Mosque, which was filled with many diverse gypsum decorations that covered most of its parts. The location and history of the Habashi Mosque and the gypsum decorations on the external facades of the mosque and the decorations of the dome that crowns the mihrab of the Habashi Mosque from the outside were studied. The gypsum decorations of the dome of the shrine attached to the mosque were also studied, as were the gypsum decorations that crown the minaret from the base and body and the muezzin's balcony and the call to prayer balcony and the top of the minaret. The gypsum windows in the mosque were also studied, as well as the decorations on the insides of the mosque's arches. Among the gypsum decorations found in the Habashi Mosque: Plant motifs, geometric motifs, and inscriptions, as well as architectural ornaments such as muqarnas and balconies.