Dong 'e Ejiao is not boiled donkey skin in the traditional sense, because the water it uses is boiled by authentic Dong 'e groundwater, which is different from ordinary boiled donkey skin. The donkey skin boiled with Dong 'e water is easy to separate colloid from impurities, and the colloid is pure. Moreover, Wang Mianzhi, a master of traditional Chinese medicine, once said that the glue boiled with donkey skin alone, without Dong 'e water, can only be called donkey skin glue, and its health care effect is very different from Dong 'e Ejiao.