The shrine of Imam Reza (AS) is considered to be the largest and the most important religious attraction in Iran, which we see throughout the history of Islam. The dynasties, personalities, and elders of each era have been refurbishing and developing this sacred place, to the extent that each section describes the art of architecture at a specific time in the history of Islamic art, including the elders and kings of the Safavid dynasty, the main reason being the recognition of the Shiite religion and the reverence and respect for the elders of this religion. The architecture of the Safavid era is a symbolic manifestation of a sublime truth, leading man from the multitude of the outside world to divine unity where one can feel the presence of God. The kings, artists, and architects of this period, with an emphasis on unity, sought to evoke divine unity in minds, creating a style known as the Isfahan style,the latest of the four Islamic architectural styles in Iran which is based on the simplicity of most designs. Allah Verdi Khan, a brave warrior and military commander of the Safavid era, has done a lot of work to promote the culture and civilization of Iran and paid special attention to the architecture of this era. This can be emphasized by looking at the works remaining from him in Isfahan (Si-o-se-Pol), Shiraz (Khan School) and Mashhad (Dome of Allahverdi Khan). The Dome is one of the most important mystical symbols. Its special form, which resembles the enameled Dome, represents the inclusion of all creation (by heaven). For this reason, the artist always imitates the Dome of heaven with large Domes in the mosques and provides the opportunity for spiritual worship to seek the blessings of divine power for believers. Dome of Allahverdi Khan, is one of the most beautiful buildings of the Astan Quds Razavi, which Arthur Pope, in the book of Iranian Architecture, considers to be the most complete part of the shrine of Imam Reza (AS). The mosaic tiles of this porch are decorated with the inscriptions and animal, plant, and geometric motifs. Many of these motifs include a concept that has a particular place in the culture and literature of this land. Since the use of peacock motif, as a decorative element, has reached its perfection in Safavid era architecture, and its use is observed in many buildings of this period, the main purpose of this paper is to study the motif of peacocks in the tiles of the above-mentioned porch. The questions are: 1-To which period most of the peacock motifs belong? 2-What is the position of this motif in the holy shrine in the Safavid era and the subsequent periods? The symbol of the peacock has cosmic, intrinsic and mythological meanings in the art and architecture of ancient and Islamic Iran. Therefore, its study as one of the most widely used animal motifs, considering the historical period, in order to grasp symbolic concepts and how to place this role and the type of attitude towards it in different periods is of importance and necessity. In this regard, the writing of this article is based on the historical-descriptive method and the use of library documents, as well as the gathering of material as a transcript, field observations, and photography of other peacock motifs on the tiles of the holy shrine of Razavi and Porch of Allahverdi Khan. Data analysis is also qualitative. In total, 132 peacock motifs from the three historical periods of the Safavids, Pahlavis and the Islamic Republic era have been studied, including 10 compositions in 17 tiled frames in the Porch of Allahverdi Khan and 6 compositions in 14 tile frames related to other parts of the shrine. Most of these motifs in the holy shrine are related to the Islamic Republic era (96), 26 to the Safavid period and 10 to the Pahlavi period. In terms of positioning, most of the peacock motifs are represented in a side view, 114 of which as guardians, while there are 18 motifs from the front view. Finally, after searching and discovering the deep meanings of this symbol, one can reach the semantic underlying layers and the reasons for its application. These tiles, consisting of physical form, layout and motif, are all intended to attain the highest order of existence, immortality and rebirth, to relate to the creator of life, blessings and fertility, as well as to pass through the temporal phase of the lowness and to connect to the highest eternal order. Repetition and symmetry also have existential and anti-mortal meanings, so there is no custom in which there is no repetition. The presence of these motifs, besides the quoted meanings, also induces these implicit meanings: unity in plurality, plurality in unity, plurality of eternity and infinity, power, spirituality, bottom-up connection, and earth to heaven.