The Dryness and the Dampness is the congential nature. the Water and Fire is the acquired action. the skin is related to the physiological function of the lung, so the skin is the domain of the lung. the lung belongs to the dryness-metal(燥金). And the Dryness and the Dampness in the six pathogenic factors exert a important pathogenic influence upon the skin. Psoriasis is a chronic skin condition charactered by red, silver scaly patches in the affected areas, it is caused by excessive growth of the top layer of the skin(epidermis). Scalp psoriasis affects at least two thirds people who have psoriasis. Generally, the scalp will have plaque psoriasis characterized by elevated, inflamed, lesions covered with silvery white scales. The lesion of psoriasis is head, elbow and knee that are yang-channels in Oriental medicine. The syndrome falls with in the purview of the dryness-metal(燥金). In time, psoriasis takes a turn for the worse in the winter season. In space, many of people in comparison to the average in the world have psoriasis in high latitude that is dry and cold, for instance, the Scandinavian peninsula. Deficiency of yin-fluid and blood course often the dryness-syndrome, for instance, psoriasis, etc. So psoriasis is one of the dryness-syndrome in Oriental medicine.