This paper focuses on how Chinese intellectuals discussed and researched rainbows in late Ming and early Qing Dynasty. Many of them considered the rainbow as a phenomenon that occurred under certain conditions of sunshine and raindrops, which could be described with terms related to qi (气) of yin/yang (阴/阳). Some of them had the knowledge of duplicating rainbows by “spraying water opposite to the sun”. There were also popular conceptions that rainbow was a sign of salaciousness and rainbow could siphon water, both of which had a long history in Chinese context. Scholars also discussed other phenomena similar to rainbow such as solar halo, lunar halo, parhelion and parselene. Those discussions were not held in wider society, yet they were the sign of how Chinese intellectuals rationalized their research into natural philosophy.