Abstract：Immunoglobulin A vasculitis with nephritis （IgAVN） is a common secondary glomerulonephritis with an unclear pathogenesis， and there is no unified standard for its syndrome differentiation and treatment in traditional Chinese medicine （TCM）. The theory of "yin-yang， water-fire， and qi-blood" is a syndrome differentiation theory proposed by TANG Zonghai， a physician in the late Qing Dynasty， which posits the interdependence of qi， blood， water， and fire as manifestations of yin and yang. The theory of "cutaneous region and collaterals" is a TCM theory centered on the "cutaneous regions" and "collaterals." Based on these two theories，the course of IgAVN can be divided into three stages： In the initial stage， the pathogenesis involves insufficiency of qi and water， pathogenic factors invading the yang collaterals， and fire-induced disorders involves the blood. The treatment principle is treating incidental aspect in the case of emergency，with therapies such as dispelling wind，releasing the exterior，nourishing yin， and cooling the blood. In the middle stage， pathogenic factors enter the yin collaterals， causing blood stasis obstructing the kidney collaterals. Treatment at this stage should target both the root cause and symptoms， by eliminating pathogens， unblocking collaterals， activating blood circulation， and resolving stasis. In the late stage， healthy qi is deficient while pathogenic factors linger， internal retention of tubidity and toxin， with great damage to kidney. The treatment principle is simultaneous application of purging and nourishing therapeutics， using therapies such as tonifying the kidney，activating blood circulation，unblocking bowel movement，and lowering turbid. At this stage，dialysis may be necessary to preserve life.