Persistent left superior vena cava (PLSVC) is a common venous variation that is usually accompanied by an absence of the left brachiocephalic vein, and displays a higher incidence in patients with congenital heart disease. Here, the case of a 57-year-old male patient who was found to have PLSVC on chest computed tomography (CT) during screening for gastric cancer metastasis at the Affiliated Hospital of Qinghai University, is described. Further coronal CT and three-dimensional reconstruction of the chest revealed the patient's double superior vena cava (DSVC), double odd veins, and left brachiocephalic vein dysplasia. The patient did not have congenital heart disease and the case was associated with dysplasia of the left brachiocephalic vein, indicating an unusual and rare venous abnormality. At the time of writing, the patient was receiving antitumour therapy.