Abstract: Applying tropical year and lunation, the exchange formula of lunar calendar and solar calendar could be derived. It begins from a given lunar date. Through several integer tropical years, the present solar date can be derived. There are three different formulas for this. On the contrary, there are another three different formulas for the exchange from solar date to lunar date in this paper.

Key words: tropical year, lunation, exchange of lunar calendar and solar calendar

摘要： 以回归年和朔望月为基础，推导出阴、阳历日期换算公式。其依据是以给定阴历为起点，经过若干整回归年，导出现在的阳历日期，本文共有3种公式。反之，再由阳历向阴历换算，又有3种公式。

关键词: 回归年, 朔望月, 阴阳历换算