Radix Rehmanniae is mainly divided into raw and cooked Radix Rehmanniae. Raw Dihuang is generally used to nourish Yin and nourish Blood, nourish Yin and produce fluid. Generally, it is used to clear heat and nourish Yin when the symptoms of Yin deficiency and fire are obvious, or when there is a deficiency of fluid, resulting in dry mouth and irritable heat. The main function of rehmanniae is to nourish blood and nourish yin and fill in the marrow. It is generally used for yin deficiency and fire exuberance caused by deficiency of kidney essence and deficiency of liver and kidney. The Chinese patent medicines such as Zuo Gui Drink, Zuo Gui Pill, Right Gui Drink, Right Gui Pill for nourishing kidney essence, nourishing kidney yin, or flattening kidney qi, nourishing kidney yang, all contain Di Huang, which has the effect of nourishing the kidney and filling the marrow. Therefore, when seeking yang in yin and yin in yang, when ping tonifying kidney qi, they usually put rehmanniae, which is the difference between raw and rehmanniae.