Why are the calendars used in China, and how?
In China, the native calendar is the "farmer's calendar" (農(nóng)歷 nónglì), as opposed to the "civil calendar" (公歷 gōnglì), or "Western calendar" (西歷 xīlì). The Chinese calendar is also known as the "old calendar" (舊歷) after the "new calendar" (新歷), i.e. the Gregorian calendar, was adopted as the official calendar.

What are the usages of Chinese calendar?

Among Chinese, the lunisolar calendar is not used for most day to day activities, unlike the Gregorian calendar, but is instead used for the dating of holidays such as Chinese New Year (Spring Festival) and the Mid-Autumn Festival

Chinese calendar is also used for divination, including choosing the most auspicious date for a wedding or the grand opening of a building.

Where does Chinese calendar originate from?
The legendary beginning of the Chinese calendar developed during the first millennium BC. The legend states that the first Chinese calendar was invented by the first legendary emperor, Huangdi or the Yellow Emperor, whose reign was assigned to 2698-2599 BC. The fourth legendary emperor, Emperor Yao, added the intercalary month. The 60-year stem-branch (干支 gānzhī) cycle was first assigned to years during the first century BC. The first year of the first cycle was assigned to 2637 BC, thus since 1984 the current cycle has been 78.

How has the Chinese calendar evolved throughout history?
The earliest archaeological evidence of the Chinese calendar appears on oracle bones of the late second millennium BC Shang dynasty. They show a 12-month lunisolar year having an occasional thirteenth month, and even a fourteenth month.

remainder) calendar, which began about 484 BC, was the first calculated Chinese calendar, so named because it used a solar year of 365? days, along with a 19-year = 235-month Rule Cycle, known as the Metonic cycle in the West. The winter solstice was in its first month and its intercalary month was inserted after the twelfth month.

Beginning in 256 BC with the Qin kingdom, which would later become the Qin dynasty, the intercalary month was an extra ninth month at the end of a year that began with the tenth month. Western Han Dynasty continued to use this timing method.

In fact, in most time of feodal society, Chinese used emperor's reign-period year based on the sexagesimal cycle. But the Boxer rebellion of 1900 left the ruler of China, weakened and vulnerable to a challenge from Chinese Republicans, who intentionally used a continuous count of years to delegitimize the Qing Dynasty by refusing to use its years.

How do you name the months according to the Chinese calendar?
Chinese have a very different constellation system. The twelve months are closely connected with agriculture, so they are alternatively named after plants. The table bellow shows it in detail.

What rules should we obey when using a Chinese lunisolar calendar?

The months are lunar months, such that the first day of each month beginning at midnight is the day of the astronomical new moon.
Every solar term of the Chinese solar year is equivalent to an entry of the sun into a sign of the tropical zodiac.

The sun always passes the winter solstice (enters Capricorn) during month 11.

Every second or third year has an intercalary month, which may come after any regular month. It has the same number as the preceding regular month, but is designated intercalary.

month occurs, it is designated intercalary, but if two such months occur, only the first is designated intercalary.

The times of the astronomical new moons and the sun entering a zodiac sign are determined in the Chinese Time Zone by the Purple Mountain Observatory (紫金山天文臺), which is outside Nanjing using modern astronomical equations.