Pulmonary hamartoma refers to a tumor-like deformity that contains all the normal tissue components of the lung, but has abnormal number, abnormal arrangement or abnormal degree of differentiation. Pulmonary hamartoma is not a true tumor (some researchers argue that it is a true tumor), but an abnormal development of the embryonic lobe, originating from normal tissue in the lung, mainly a tumor-like lesion formed by cartilage, fibrous connective tissue and adipose tissue. Because its nature and imaging characteristics are similar to benign tumors, it is classified as a benign tumor. According to its composition, it is divided into cartilaginous type and fibrous type. According to the location, it is divided into central type and peripheral type. Occurring in the submucosal membrane of the trachea and lobar bronchus is called central type. Occurring in the lungs is called peripheral type, and peripheral type is mostly located under the pleura.