Renal involvement of systemic small-vessel vasculitis is clinically a critical illness. Although many novel immunosuppressants, such as biological agents, have improved the clinical remission rate of the disease, the efficacy is still not satisfactory due to high recurrence rate, high infection rate, and high rate of progressing to end-stage renal failure. So many scholars explore the treatment with integrative traditional Chinese and western medicine in order to improve its clinical efficacy. By means of the literature review and their own clinical experience, the authors advocated the application of collateral disease theory of traditional Chinese medicine (TCM) into the syndrome-differentiation treatment of this disease. The disease position is at the blood collaterals, and its basic pathological feature is block of collaterals. The pathogenesis is characterized by the deficiency in origin and excess in evil, and blood stasis is through the whole course of disease. The treatment should be carried out according to the different stages of disease, grasping the dialectical relationship between the unblocking therapy and reinforcing therapy.