The twenty-four solar terms of the lunar calendar were formed by ancient China people's cognition of the four seasons, () and phenological changes in a year.

The twenty-four solar terms of the lunar calendar were formed by ancient China people's understanding of the changing laws of seasons, climate and phenology in a year. The 24 solar terms are: beginning of spring, Rain, Sting, Equinox, Qingming, Grain Rain, Changxia, Xiaoman, Mangzhong, Summer Solstice, Xiaoxia, Daxia, beginning of autumn, Chushu, Bailu, Autumn Equinox, Cold Dew, First Frost, beginning of winter, Light Snow, Heavy Snow, Winter Solstice, Slight Cold and Severe Cold. ? The current "twenty-four solar terms" are formulated according to the position of the sun on the return to the ecliptic, that is, the annual movement track of the sun is divided into 24 equal parts, each 15 is 1, and each 1 is a solar term, starting in beginning of spring and ending in severe cold.

In Shang dynasty, there were four basic solar terms, namely, midsummer, midsummer, midsummer and midsummer, but in Zhou dynasty, the solar terms increased to eight. Twenty-four solar terms appeared for the first time in the history books of Huainanzi, and the Han Dynasty was also one of the times laid by China's calendar method. "Twenty-four solar terms" is called the national legal calendar. Using soil gauge to measure the sun shadow to determine that the shortest solstice of the winter solstice is in the Western Han Dynasty. Taking the winter solstice as the starting point of the year, it is divided into 24 points from now on, and the solar calendar in the China lunar calendar is basically finalized.