This study deals with the general history of the calendrical calculation system and annual calendar of the Goryeo(高麗) Dynasty, which have hardly been studied because of the lack of records. Along with the official records of the Goryeo Dynasty, Goryeosa(高麗史, Official History of Korea) and Goryeosa-jeolyo(高麗史節要, Essentials of Goryeo History), this study explores various Chinese references and collections of the literary works(文集) of numerous scholars in the Goryeo period(918～1392). First of all, this study clarifies that there were two kinds of annual calendars in Goryeo. One was published by the Goryeo astronomers every year, and the other was submitted to the Goryeo Kingdom by a neighboring kingdom in China as a symbol of investiture under the tribute-investiture system(朝貢-冊封 體制). By collating the arrangement of intercalary months(閏月) of Goryeo with that of neighboring kingdoms, this study shows that the calendrical calculation system of Goryeo was not accordant with the common notion that Goryeo exclusively used Xuanmingli(宣明曆, Extending Enlightenment Calendar) system of the Tang Dynasty from the beginning of the Dynasty to the early 14th Century when the Shoushili(授時曆, Season Granting Calendar) system of the Yuan Dynasty was implemented in Goryeo. Particularly in the 11th Century, when Goryeo paid tribute to Liao, the arrangement of the intercalary months of Goryeo was far more similar to that of Song than Liao, while Liao’s was similar to that of Japan, where the Xuanmingli system was definitely implemented. This study concluded that, in the 1th Century at least, Goryeo used a different system from Xuanmingli. Goryeo introduced the Shoushili system from Yuan China and issued its annual calendar from the year of 1309, and this practice continued into the Joseon(朝鮮) Dynasty. The annual calendar of Goryeo was often called Dongjiryeok(冬至曆) because it was issued on the day of the winter solstice. The style of the calendar is thought to be typical Juzhuli(具注曆, annotated calendar), which combined the two main contents, the calendrical dates(曆日) and the fortune note(曆注), for conducting daily life. Annual calendars were issued to the government offices and bureaucrats, and intellectuals exchanged them as a gift.