Choosing a day is also called choosing an auspicious day. Choosing auspicious days is a subjective behavior of human beings to seek and yearn for a safe and auspicious living environment in order to meet their survival needs. The purpose of choosing auspicious days is to hasten good luck and avoid evil, and it is an effort for human beings to choose and use favorable conditions to avoid and overcome unfavorable factors, so as to obtain auspicious peace and avoid near benefits and far harm, which is also human nature or instinct. We use wisdom and experience to find and determine the right time and space for various activities in the world. It is mainly to fully grasp the timely opportunities brought by the harmonious relationship between time, place, people and the above as much as possible. At the same time, choosing good luck can also meet people's psychological needs and increase people's confidence and determination.