According to technical presages, in the preliminary studies, we have found that there are at least 12 different kinds of stucco decorations belonging to the Islamic periods of Iran. Technical executive details in each kind of these decorations depending on composition and method of treatment, manner of forming, and measure of relieve are different. Unlike two common categorizations which are based on method of forming and/ or measure of relieve, this kind of new categorization has founded on technical details and executive methods. Therefore it can be more suitable for conservation and restoration goals, technological and archeological aims, as well as in scientific research for understanding and presentation of traditional methods and technology used to create these works of art. The results of these studies have lead us to a technical classification of stucco decorations that contains: high relief, semi relief, mould stucco, Koshtehbori, Cupbori, combined with tile or glass, Tongbori, lattice, and coiled paste on the flat mirror, combined with Simgel, and mosaic stucco decorations.