Zhenbudang astronomical calendar refers to a method of astronomical calendar calculation created and passed down by four generations of the Cai family in Longjiang, Shunde. The founder, Cai Shoucai, studied calendar intensively and founded Zhenbudang on Gaodi Street in Guangzhou in the 17th year of the Guangxu period (1891). He wrote works such as "Seven-point calendar" and "Arctual and angle seven-political diagrams", and created the astronomical calculation method of "using diagrams instead of calculations", which became a supplement to the "Armillary sphere instead of calculation method", achieving the scientific effect of "seeking the twelve palaces and seven political systems of life to the plane of the earth", and became a famous date selection expert in Guangdong Province. Zhenbudang astronomical calendar is based on the astronomical calculation rules of successive dynasties and the astronomical calculation rules of the Cai family, pursuing the perfect coordination of the calculation mode of the solar and lunar cycles in the calendar to achieve the unity of yin and yang. It has well preserved the achievements of traditional astronomical calendars and the guiding rules of various folk customs, and has very rich folklore information. It is the first-hand material for interpreting folk beliefs and folk culture in the Pearl River Delta region, and has precious folklore value, cultural value and historical research value. On November 22, 2013, Zhenbudang Astronomy and Calendar was included in the fifth batch of Guangdong Province's provincial intangible cultural heritage list.