Pulmonary artery trunk widening means that the width of the pulmonary artery is greater than the upper limit of normal width. Pulmonary artery trunk widening is mainly caused by increased pulmonary artery pressure, and the main causes of increased pulmonary artery pressure are pulmonary heart disease and some congenital heart diseases. The main cause of pulmonary heart disease is chronic obstructive pulmonary disease, while chronic pulmonary heart disease is mainly caused by chronic bronchitis, and may also be caused by chronic pulmonary artery embolism, which is caused by increased resistance to pulmonary artery widening. This may also be caused by congenital heart disease such as atrial septal defect or ventricular septal defect, where left-to-right shunt leads to increased pulmonary artery blood flow, causing widening of the pulmonary arteries, which is further aggravated by pulmonary hypertension due to necrosis and occlusion of the distal pulmonary arteries. Therefore, when widening of the pulmonary artery trunk occurs, it is generally in a pathological state and should be actively sought for the primary cause and treated aggressively.