Abstract: Objective To study the etiology, clinical characteristics, treatment and prognosis of Acute nephritis syndrome with lung injury, so as to improve identification and clinical diagnosis and treatment levels of this disease. Methods The patients with acute nephritis syndrome with lung injury diagnosed from January 2011 to November 2015 were selected in this study. Their general information, laboratory indexes, imaging features and renal pathological features were collected and analyzed; These patients were followed up for 3 years after diagnosis to investigate the prognosis of the disease. Results In this study a total of 23 patients with acute nephritis syndrome with lung injury were enrolled; they aged 11~70 years with the average age of (47.2±17.9) years, with no significant difference between male and female. The patients included 12 males and 11 females, and both males and females were symptomatic. There were 4 patients with positive anti-GBM antibody among the 23 patients, with 1 patient showing double-positive for anti-GBM and antineutrophil cytoplasmic antibody (ANCA). ANCA was detected to be positive in 19 patients, with 1 patient showing positive ANA and dsDNA. All the 23 patients had cough,14 ones of them had hemoptysis,15 ones had recent typical pulmonary hemorrhage with flaky or diffused infiltrating shadow in the CT images, and 8 patients had pulmonary interstitial changes characterized by grid-shaped shadow in the lung CT images. Comparison between various groups showed that anemia severity and creatinine increase in the pulmonary hemorrhage group were higher than those in the pulmonary interstitial change group (both P<0.05). By survival analysis it was found that 3-year survival in the pulmonary interstitial change group was higher than that in the pulmonary hemorrhage group, with no statistically significant difference (P>0.05). Among the 14 biopsied patients, 13 patients suggested presence of crescents nephritis-III type, and 1 patient had pathological symptoms of diffused lupus nephritis (type IV). The syndrome is hard to detect and progress quickly, in most cases pulmonary pathological changes may be improved through immunosuppression therapy, and the overall prognosis is poor. After 3 years of follow-up, 5 patients died, 9 patients entered maintenance hemodialysis treatment, and 6 patients experienced chronic renal insufficiency without dialysis, and 3 patients had normal renal function.Conclusions Acute nephritis syndrome with lung injury has multiple etiology, a rapid clinical progress and poor prognosis. Identification of the etiology and the resulting targeted treatment are essential for diagnosis and prognosis of this disease..