Pulmonary nocardiosis (PN) is a severe infectious disease caused by Nocardia. It is clinically rare and is easily misdiagnosed as other bacterial, fungal, pulmonary infectious diseases (e.g., tuberculosis), tumors, vasculitis, etc. PN often occurs in hosts with compromised immunity. The symptoms are mainly fever, cough, expectoration, etc. The imaging manifestations include consolidation, nodule, mass, cavity, etc. The typical pathological damage of the lung is necrotic abscess, and granuloma emerges in patients with chronic infection. There are no specific serological markers, hitherto. Laboratory tests show that peripheral blood leukocytes, C-reactive protein, and other inflammatory indicators increase, and low lymphocytes and hypoalbuminemia are also common. The diagnosis relies on etiology. Under the microscope, Nocardia presents multidirectional branching filaments. The colony is white, yellow, or purple, and its surface is powdery or velvety. Culture takes a long time, which is easy to cause missed diagnosis. Molecular techniques are helpful for diagnosis. The treatment should be adequate and individualized, and the drug sensitivity test should be taken as the guidance. Sulfanilamide is the main treatment drug, and combined therapy can be used as the initial treatment. Early diagnosis and timely treatment are the key to the prognosis.