In recent years, the incidence of pancreatic diseases in China has been on the rise. Clinically, we often meet patients who come to the clinic because a pancreatic mass is found, and many of them are in a dilemma in the face of the imaging unknowns. Because to clarify the nature of the pancreatic mass, if there are no typical disease symptoms and laboratory evidence, the pancreas is hidden so deeply that it is not easy to take a sample by ordinary methods; nor can we perform a very invasive open surgery in order to take a sample, which would not be putting the cart before the horse. In this case, endoscopic ultrasonography (EUS) can be of great help. Endoscopic ultrasonography, commonly known as an ultrasound probe added to the front of the gastroscope, can be twice as effective. The ultrasound probe is brought through the gastroscope to the stomach and duodenum close to the pancreas for examination. Because the ultrasound endoscope probe is close to the pancreas, the frequency of the probe is high, and the interference of gas, bone and fat in the gastrointestinal tract is avoided, it can form a high definition image of the pancreas and can detect pancreatic masses smaller than 1cm, and even masses of about 5mm in diameter can be detected. It is also the most promising machine to detect early pancreatic cancer, which cannot be done by CT, MRI, or ordinary ultrasound; meanwhile, it is very sensitive to the situation around the mass and to the tiny vascular infiltration and lymph node metastasis of the tumor, which are of great value to clarify the nature of the pancreatic mass. Just like gastroscopic biopsy, ultrasound endoscopy-guided fine-needle aspiration biopsy (FNA) is now very mature and has become an excellent method to clarify the nature of pancreatic masses. In general, EUS-FNA has a specificity of 99%-100% and a sensitivity and accuracy of over 90%. By inserting the puncture needle through the biopsy hole of the ultrasound endoscope, the ultrasound at the front end of the endoscope is close to the examination site and clearly shows the lesion and its boundary, which makes the location of the puncture sample more reasonable and the success rate of obtaining the specimen is very high; because the puncture is performed with a fine needle, the tissue damage is light and the complications are minimal. At the same time, during the puncture process, the ultrasound at the front end of the endoscope can always “see” the puncture needle and observe the whole process of needle insertion, avoiding the surrounding organs, blood vessels, nerves and other important tissues, almost “pointing there and hitting there”, so it is very safe and can make many unidentifiable pancreatic masses to be detected. Therefore, it is very safe and can enable many pancreatic masses that cannot be clearly identified to be diagnosed and avoid open surgery. It is less risky, less damaging to the body, easier to operate and more economical than ordinary ultrasound and CT-guided pancreatic puncture. The tissue fluid and tissue strips obtained from pancreatic EUS-FNA are sent for pathological, biochemical and immunological analysis, which can provide important help for subsequent treatment. EUS-FNA indications: 1, pancreatic cancer and its preoperative staging, especially before radiotherapy and chemotherapy. 2. Inflammatory masses of the pancreas. 3.Neuroendocrine tumor. 4.Cystic lesions of the pancreas. 5.Suspected chronic pancreatitis. 6, Pancreas and most of the peri-pancreatic area such as the lower bile duct and adrenal glands. 7.Abdominal occupancy. 8.The nature of micro ascites. 9, Biopsy of retroperitoneal lymph nodes.