The first argument is that some people think that the pronunciation of Qing and Jin in Manchu is basically the same, so Huang Taiji changed the name of Qing, but this argument may be unacceptable to many people because the pronunciation is actually very similar. Why change it? The second view is from the perspective of feng shui. Before Nurhachi established a new dynasty, it was the Ming Dynasty. One day on the left this year, it represented fire on the five elements of Feng Shui, in order to suppress the remnants of the Ming Dynasty and prevent them from restoring the Ming Dynasty. Huang taiji changed the title of golden title to Qing, next to which is the three-point water, which also represents the water in the five elements to suppress fire.
There is another explanation from shaman culture. Some people say that because the word "Qing" has a more auspicious meaning in shaman culture, Qing and Qing are homophonic, so Huang Taiji changed his country name. But many people don't agree with this statement, thinking why not use the green word with auspicious meaning, but choose the clear with three waters.
In addition, there is a folk saying that Nurhachi was defeated in a war, and then fled on a big blue horse to help him escape but died of overwork. So it's to commemorate this big green horse. Later, Huang Taiji also changed his country name to Qing according to Nurhachi's wishes. But these statements are all speculated and fabricated by people, and there is no historical record, so we don't know what the real situation is.