The book includes translations and studies of the works of al-Khorezmi, which were one of the first astronomical works in the Near and Middle East. They outline issues of theoretical and practical astronomy, chronology, trigonometry. These treatises played an important role in the formation and development of astronomy in the countries of the East and Europe. The main merit of al-Khorezmi in the history of astronomy is the compilation of trigonometric and astronomical tables ("Zij al-Khorezmi"), which served as the basis for medieval research in this area both in the East and in Western Europe. Although (Zij al-Khorezmi is mainly a processing of Brahmaguphut Siddhanta by Brahmagupta, many of the data in it are given at the beginning of the Persian era of Yazdegerd and, along with the Arabic names of the planets, their Persian names are given in the tables of equations of the planets of this zij. The Treatise on the Calculus of the Jewish Era also adjoins this ziju. The "Book of Chronicles" of al-Khorezmi, mentioned in various sources, has not been preserved. The book is designed for specialists in the theory and history of science, in particular, the history of astronomy.