The Calendar(曆法) has been a very important concern in every dynasty of history. 『Hyupgiltongui』 written in the Joseon Dynasty included many contents related to the Calendar. In particular, the ancient rule of the Calendar(曆律) shown in the text of 『Hyupgiltongui』 Bonwon chapter one is meaningful in the process of creating the necessary Calendar for selection and reading fortune. Accordingly, we tried to analyze the rule of the Calendar(曆律) that is the fundamental principle of the Calandar(曆法) and the almanac which can be used in real life, based on comparative analysis of 『Hyupgibyeonbangseo』, 『Sanggiltongseo』 and 『Cheongidaeyo』, which are the basis of 『Hyupgiltongui』. Saju Myung-ri is the scheme of time change by the combination of Ganji(Celestial Stems). Therefore, the core of the calendar system is to make four pillars by the year, month, day, and time. For doing this, 『Hyupgiltongui』 provides basic principles and materials for making four pillars using constellations like 28 Fixed Stars, as well as does simple composition principle for telling fortune such as Ten Celestial Stems, Twelve Zodiac Signs, the order of four seasons(四序), Yukjin(六辰) and Sexagenary Cycle (甲曆). However, despite the limitations of the results produced by the rule of the Calendar(曆律), we came to the conclusion that if reading fortune in Saju(四柱簡明) is to find good one(吉) in terms of understanding it as the rule of predicting future(術法) not science, its usefulness cannot be ignored.