Traditional pottery pots, crocks and ceramics do not react with various Chinese medicine ingredients, and the heat transfer is even and slow, and the quality of the decoction is good. Stainless steel is a passive element, which is not easy to produce chemical reaction. Now many big hospitals have water separators made in stainless steel pot. The iron frying pan, although it has fast heat transfer, is not only easy to be oxidized, but also unstable in chemical properties. It can form iron tannic acid with tannin, deepen the color of soup, and form insoluble complex with flavonoids.