Objective：To analyze the lung involvement characteristics of microscopic polyangiitis（MPA） and its treatments with the purpose of improving the awareness of it and the diagnosis and treatment for it. Methods：The clinical data of 94 MPA patients with lung involvement admitted into The First Affiliated Hospital of Chongqing Medical University from May 2011 to October 2016 were retrospectively analyzed，including the clinical manifestations，laboratory test results，chest imaging features，pathological features，treatment，prognosis etc. The main clinical manifestations，laboratory test results and chest imaging features were compared between patients with respiratory symptoms as initial symptoms（group A，n=34） and patients with non-respiratory symptoms as initial symp－toms（group B，n=60）. Results：The patients included 49 males and 45 females，with the mean age as （65.2±10.9） yeas. In MPA pa－tients with lung involvement，main manifestations were cough，expectoration，hemoptysis and dyspnea，and 21 patients were found with respiratory failure. The characteristics in chest CT/HRCT included the following patterns，patchy consolidation or ground-glass opaci－ties（n=61，64.89%），reticular or honeycombing（n=13，13.83%），and both of the former two（n=20，21.28%）. Twelve cases（12.77%） had radiographic evidences for usual interstitial pneumonia（UIP），and 30 cases（31.91%） cases for diffuse alveolar hemorrhage（DAH）. The incidence of respiratory symptoms in group A was significantly higher than that in group B（P<0.05），including cough/expectoration（32/34 vs. 46/60），hemoptysis（15/34 vs. 13/60） and dyspnea（27/34 vs. 20/60）. No significant differences were found between group A and B in constitutional symptoms and other extra-pulmonary manifestation（P>0.05），such as fever（24/34 vs. 37/60），rash（3/34 vs. 8/60），hematuresis（22/34 vs. 41/60），proteinuria （21/34 vs. 40/60）. The incidence of DAH in chest CT was sig－nificantly higher in group A than that in group B（18/34 vs. 12/60，P<0.05）. A total of 82 patients who accepted treatment were treated with glucocorticoids and immunosuppressive agents，among which，11 severe/life-threatening patients were treated with intravenous pulsed methylprednisolone with cyclophosphamide. Conclusion：The prevalence of lung involvement in patients with MPA is high，and pulmonary fibrosis and DAH are the special radiological findings. DAH is more likely to occur in patients with respiratory symptoms as initial symptoms. Glucocorticoids combined with immunosuppressive agents are the main treatment of MPA patients，whose short-term prognosis is relatively good.