It is sometimes difficult to distinguish mediastinal tumors from primary or secondary lung tumors, enlarged lymph nodes and hemangiomas in morphology. Commonly used examination methods are as follows: 1. X-ray examination: fluorescence fluoroscopy found that the tumor has pulsation, which should be clarified as dilatation or conduction pulsation first. If it is the former, it can be initially suspected as aneurysm, which can be confirmed by X-ray radiography or angiography. If the upper mediastinal tumor moves upward with swallowing on X-ray fluoroscopy, it can be initially diagnosed as thyroid tumor. Plain X-ray film, stratified film, or high-thousand-volume X-ray film in front, side and oblique position can clarify the location, shape, density, calcification or ossification of the tumor, so as to make preliminary judgment on the type of the tumor. Barium swallow examination of esophagus can find out whether the esophagus or adjacent organs are compressed. 2.Fiberoptic bronchoscopy or fiberoptic esophagoscopy: It can help to clarify the situation and degree of bronchial pressure, whether the tumor has invaded the bronchus or esophagus, so as to estimate the possibility of surgical resection. 3.Diagnostic pneumothorax: It can determine whether the tumor occurs in the chest wall or lungs, inside or outside the lungs. Diagnostic pneumothorax can distinguish subphrenic factors, such as diaphragmatic hernia. 4.Mediastinal pneumography: it is quite helpful to show the morphology of anterior mediastinal tumor and clarify whether there is mediastinal lymph node metastasis. 5.Mediastinoscopy: It is helpful to clarify whether there are enlarged lymph nodes under paratracheal and rongeur, and biopsy can be taken to clarify the etiological diagnosis. 6.Computerized tomography: CT examination of anterior mediastinal tumor, enlarged lymph nodes, mediastinal fat tissue lesions is more reliable than any other X-ray examination method; the accuracy of CT diagnosis of mediastinal tumor and enlarged lymph nodes can be more than 90%. 7.Magnetic resonance imaging: it has the following advantages: many imaging parameters; high resolution of soft tissue; flexible direction of cut layer; no bone artifacts in the image; safe and reliable, no ionizing radiation damage. It is unique in diagnosing mediastinal tumor. 8.Biopsy of cervical lymph nodes: bronchial lymph node tuberculosis and lymphoma are often accompanied by peripheral lymph node and cervical lymph node involvement, and biopsy is helpful for diagnosis. 9.Radionuclide examination: suspecting intrathoracic goiter, radionuclide 131 iodine scan can be made, which is helpful for the diagnosis of ectopic goiter and thyroid tumor. 10.Diagnostic radiotherapy: when malignant lymphoma is suspected and not confirmed by other examinations, radiotherapy can be tried. Malignant lymphoma is more sensitive to radiation, with irradiation of 20~30Gy (2000~3000rad), the tumor will shrink rapidly. 11. Cesarean section: if the nature of the tumor cannot be clearly defined after various examinations, but malignant lymphoma is excluded, under the permit of systemic condition, cesarean section can be performed.