This paper analyzes how the 27th August of the lunar calendar came into being and its reliability: as Liang Yu Suo said, the 22nd year of Lu Xianggong in Historical Records and October Gengzi Day in Guliang Biography are combined, which is the 22nd year of Lu Xianggong. Then, according to the "Three Meanings Theory", the October of Zhou Zheng was changed to August of Xia Zheng, and the Japanese "Gengzi" was converted into the digital calendar "Twenty-seven", and "August 27th of the 22nd year of Duke Lu Xiang" came out. However, Historical Records only records the twenty-two years of Duke Xiang of Lu, and there is no official support for Confucius' birthday, while the October Gengzi Day in Biography of Gu Liang is the twenty-one years of Duke Xiang of Lu, so it is obviously unreasonable to combine the two into one. From the perspective of calendar development, the Warring States period was the day of dry support, and the date of "Twenty-seven" is unlikely to be recorded in the early years of the Western Han Dynasty. Oracle Bone Inscriptions in Yin Ruins adopted the date of dry support. Mr. Xu Xitai said: "There are' all blessings',' all spirits' and' all deaths' in Oracle Bone Inscriptions, which shows that Yin's method of marking the day with the moon has been used now." However, in Shangshu and unearthed bronze inscriptions, there are a large number of descriptions of the auxiliary dates of the moon phases, namely the hegemony of birth, the hegemony of hope and the hegemony of death. The achievements of Xia, Shang and Zhou dynasties tend to be "four phases of the moon", and the fixed leap law of the Western Zhou Dynasty is summarized as: 1. The calendar of the Western Zhou Dynasty adopts "New Moon" or "New Moon" as the first month. Before you know the new moon, you should take "Bi" as the first month. 2. The establishment of the Western Zhou calendar is mostly for the sake of building children and ugliness. 3. The Western Zhou calendar generally adopts leap at the end of the year. This shows that the calendar level at that time had not reached the level of "seasonal calendar". Regarding the calendar, Jia Kui said, "Take taichu calendar as an example. In the first year of Tai Chu, we made 23 eclipses. Seventeen of them are new, four are unlucky and two are two days. In the new calendar, seven days are new, fourteen days are bad and two days are two days. Take taichu calendar as an example. I did twenty-four things in the second year after I turned over a new leaf in the first year of Taichu, and got ten bad results. In the new calendar, you get a new moon on 16, two days on the 7th, and one is unlucky. Take taichu calendar as an example. In the first year of Jianwu and Yongyuan, twenty-three things were done, five new things and eighteen bad things. The seventeenth day of the new calendar is the new moon, the third day is cloudy, and the third day is the second day. " "History of the Five Elements of Han Dynasty": "Every twelfth century of Han Dynasty, 2 12 years, eclipses are fifty-three, new moon fourteen, new moon thirty-six, and the first three days." The Book of Laws and Calendars of the Later Han Dynasty records: "Three calendars have been in use since the first year of Taichu, and have been implemented for more than a hundred years. The calendar is later than the sun, and the new moon is earlier than the calendar, or at dusk, month or new moon. " Judging from the calendar level of the Western Zhou Dynasty and the Han Dynasty, it is impossible to accurately predict the Shuori in the Spring and Autumn Period, but the "Sun has food" recorded in the Spring and Autumn Period is on the Shuori. What is the reason why the new moon can coincide with the solar eclipse in the Spring and Autumn Period? We speculate that in the spring and autumn period, the date of the new moon can only be set at more than 29 days and less than 30 days in a month, and the date of the new moon can be adjusted at any time according to the solar eclipse. For example, as Shuo Wen said, "The eclipse is new, and the eclipse is expected." The "new moon" related to the solar eclipse in Spring and Autumn Annals is not calculated in advance, but recorded after the solar eclipse and recorded in the book, so it is so accurate that it can be regarded as one of the contents of "Everything depends on the sun". The date is uncertain, so it is impossible to record the date in numbers. The date of the number should be after the appearance of the "Four Seasons Calendar" recorded in Li Shu Jiazi. The size of the new moon and the month can be accurately determined by the method of "day of the month, day of the month, day of the month" in the calendar, and then the digital calendar became popular. Judging from the existing literature, the digital calendar in China probably began at the end of the Western Han Dynasty and became more and more popular in the Wei and Jin Dynasties. In Chu bamboo books, it is still the official date, and there are also digital dates in Shulehe bamboo slips, which are generally considered to be the Eastern Han Dynasty. Some people think that "the time limit of Shulehe bamboo slips is from 98 BC to AD 137", but it will not be earlier than the Second Biography of Gu Liang and Ram. The "August 27th" of Kong's genealogy is unlikely to be recorded in the early years of the Western Han Dynasty, but should be recorded by later generations.