This paper introduces Professor Wu Yaonan’s clinical experience in treating chronic liver disease from the perspective of “membrane source”. Professor Wu believes that disease caused by latent evil in the membrane source has the same pathogenic characteristics with chronic liver disease; the liver is located in the middle jiao and is a part of the digestive system, which is similar to the location of disease in membrane source, so “Dayuan Drink” and the method of “clearing the membrane source” can be used to treat chronic liver disease from the perspective of “membrane source”. And two proven cases are given for discussion.