${ulcorner}$Hwangje-Naegyeong${lrcorner}$ recorded The Twenty Eight Constellations(二十八宿), the polaris, the Seven stars(北斗七星) and the Five stars(五星) and it accepted the astronomy of that time. The Twenty Eight Constellations assinged seven stars in the four cardinal points according to the ecliptic and became the criterion obsevering the way of the sun and the moon. ${ulcorner}$Hwangje-Naegyeong${lrcorner}$ explained that The Twenty Eight Constellations bring about the change of weather and role as criterion about the Universe Gate-Earth Door(天門-地戶). The Five Elementary attachment of the Twenty Eight Constellations is based on the direction of the earth in spring. The direction of the Twenty Eight Constellations changes from the viewpoint of celestial body in other seasons. ${ulcorner}$Gugungpalpung-pyeon(九宮八風篇)${lrcorner}$ and ${ulcorner}$Selo-pyeon(歲露論)${lrcorner}$ explained that the azimuth of the polaris and the Seven stars are related to the change of weather. ${ulcorner}$Gigyobyeondaelon(氣交變大論)${lrcorner}$ said that we can predict the Taegwa(太過 or Bulgeub(不及) of O-un(五運) by the orbital tracks and magnitude of the Five stars. It means that the astronomical observation is correctly performed in that time. The learning of Un-Gi(運氣學) is the study on the reciprocal action of heaven and earth. Besides the changeable disease during the 24 solar terms is related to climatic change produced by movements of heavenly bodies. For this reason, I think that the understanding of astronomical background will help to research The learning of Un-Gi.