Objective To analyze the TCM syndromes and syndrome characteristics of patients with pulmonary injury of antineutrophil cytoplasmic antibody（ANCA）-associated vasculitis（AAV）,and explore its etiology and pathogenesis.Methods The four-diagnosis information and syndrome differentiation data of the hospitalized patients diagnosed with lung injury due to AAV for the first time,were collected from May 2014 to October 2019,and retrospectively analyzed.Results In this study,the high frequency of pulmonary symptoms was cough（21/21,100%）,expectoration（19/21,90.5%）and shortness of breath（17/21,81.0%）; the main extrapulmonary symptoms were fever（13/21,61.9%）,muscle and joint pain（12/21,57.1%）,fatigue（10/21,47.6%）and anorexia（10/21,47.6%）.The incidence of muscle and joint pain in the active period（10/13,76.9%）was higher than that in the stable period（2/8,25%）,with a statistical difference（P<0.05）. The top 5 most high frequent types of syndromes were dampness invasion（52.4%）,lung-qi deficiency（47.6%）,internal phlegm dampness accumulation（38.1%）,spleen-qi deficiency（33.3%）and kidney-qi deficiency（33.3%）.The frequency of dampness syndrome（11/13,84.6%）was higher in the active period,and the frequency of blood stasis syndrome（4/8,50.0%）was higher in the stable period（P<0.05）.Among them,dampness invasion syndrome was related to the increase of Birmingham Vasculitis Activity Score（BVAS）and erythrocyte sedimentation rate（ESR）,and the difference was statistically significant（P<0.05）.The main causes were dampness,phlegm,heat and blood stasis.The basic pathogenesis is rightness deficiency and evil excess.The deficiency of lung,spleen and kidney is the root,and phlegm,dampness,heat and blood stasis are the branches.Lung,spleen and kidney are the main regions of the disease.Conclusion The clinical symptoms of lung injury due to AAV are complex and diverse,mixed with deficiency and excess.The basic pathogenesis is deficiency and excess.Lung,spleen and kidney are the mainly affected regions.