Abstract: This paper discusses the etiology, pathogenesis, course characteristics and clinical symptoms of Henoch-Schonlein purpura nephritis based on the theory of 'pathogen lodging in Shaoyin'. The deficiency of kidney yin is the primary condition of hidden pathogen storing in the body.The inducing factors were exposure to six excesses，diet irritation and contact with allergic substances．External evil is from the surface into the inside, gathering in the throat.It turns into heat after along period of time and becomes a latent fire. The latent fire consumes the fluid and blood and becomes stagnated. The stagnated fire is interconnected and becomes disease of the nest, and stays at kidney collaterals. Latent fire goes outside, and the conflict occurs between pathogenic qi and vital qi. The heat damages the blood collaterals, blood overflows to the skin, and blood seeps to urine, then skin ecchymosis or hematuria occurs.The latent fire is hidden and thepathogenic qi and vital qi are not in conflict, then there is no hematuria or skin ecchymosis. The latent and recurrent process of pathogenic qi is the basic feature of insidious pathogenic diseases.The treatment often depends on its stages, including acute stage and remission stage. In the acute stage, the treatment methods are clearing latent fire, activating blood circulation and dispelling blood stasis. In the remission stage, the treatment methods are nourishing Yin and blood and repairing kidney veins. Fumai decoction, Didang decoction and Liuwei Dihuang pill can be used flexibly in a comprehensive treatment for Henoch-Schonlein purpura nephritis. Eliminating the disease nest and removing the insidious pathogens can stop and reverse the persistent and refractory disease of nephritis.

Key words: Henoch-Schonlein purpura nephritis, Pathogen lodging in Shaoyin, Kidney yin deficiency, Insidious pathogen theory