Wulingsan syndrome is manifested with， on one hand， consumptive thirst and inhibited urination， which are caused by unrelieved exterior pathogens and blockage of muscular interstices leading to disturbance in functioning of Qi; on the other hand， thirst without desire for drink， or no feeling of thirst， or vomit after drinking， which are caused by inability of body fluid to disperse due to internal watery retention and obstruction of Qi. Both symptoms are caused by body fluid deficiency due to dysfunction of Qi transforming. The functions of cassia twig in wulingsan is to warm yang in order to transform qi and resolve dampness， which embodies the thought of “moistening with acridity” in Nei Jing.