Clubbing finger is a characterized physical finding in many diseases. Its pathophysiology is still uncertain. But this striking symptom and sign gives the physician an important clue to make the differential diagnosis. We report the case of a 57-year-old female who was admitted to our hospital with chief complaint of clubbing fingers and bone pain. The serial examinations showed possible hypertrophic pulmonary osteoarthropathy (HPOA) throughout the bilateral pelvic bones and the long bones of both lower limbs, with a lobulated nodule in the right middle lung and multiple small nodules in both lung fields. The CT-guided biopsy pathologic study of this pulmonary nodule was adenocarcinoma. Due to the advanced stage of the lung cancer, she received chemotherapy, after which, the clubbing fingers improved. We conclude that the HPOA of this patient was probably caused by the lung cancer.