Abstract: One case of rheumatoid arthritis (RA) with acute fibrinous and organizing pneumonia (AFOP) was admitted.  The clinical manifestations of this patient were mainly fever,  hypoxemia,  dyspnea,   some dry and wet rales in the lungs,  chest CT manifestation for lung consolidation and a little pleural effusion. The rheumatoid factors and antiCCP antibody greatly increased. “Fiber ball” was seen by CTguided pulmonary biopsy. The patient was diagnosed as RArelated AFOP. And lesions absorption improved after the hormone therapy. AFOP,  a rare clinical disease with high mortality,  is easy to be diagnosed as severe pneumonia. Lung pathology is the gold standard for the diagnosis of AFOP,  hormone is the main therapeutic schedule for the disease,  and  early confirmed diagnosis is the key to  prognosis.

Key words: cryptogenic organizing pneumonia, arthritis, , rheumatoid, acute lung injury