Abstract: Objective To study the clinical features,therapeutic effect,and prognosis of pulmonary alveolar proteinosis（PAP）. Methods Clinical data about 9 cases of PAP（4 males and 5 females） were retrospectively analyzed with its related literature reviewed. Results The onset age of PAP was 42 years（mean 29-65 years）.The main clinical manifestations included dyspea in 6 cases,cough in 4 cases,expectoration in 2 cases,and fever in 1 case.No symptom was observed in 2 cases.Chest X-ray showed different lesions and high resolution computerized tomography（HRCT） revealed geographic and "crazy-paving" lesions throughout both lungs.Diagnosis of PAP was established by radio-assisted transbronchoscopic lung biopsy（TBLB） and bronchoalveolar lavage fluid（BALF）. Conclusion PAP is mainly characterized by dyspea and cough,geographic and "crazy-paving" lesions throughout both lungs found in HRCT,and is diagnosed based on the findings in TBLB or BALF.Large volume lavage of the whole lung is an effective and safe therapeutic procedure for it.