Pseudocysts of the pancreas are formed in about 20-30 days. They are usually formed when the patient has acute pancreatitis, resulting in the accumulation of exudate around the pancreas and covered with a layer of fibrous granulation tissue, and then formed as pseudocysts after pancreatitis surgery. Most of them occur in the cavity of the small omentum, and some of them are in the pelvis, pubic area, mediastinum or thoracic cavity, and its characteristic is that some of the pseudocysts can disappear on their own in about 6 weeks after the onset. If the cyst does not disappear within 42 days but increases in size, a series of complications may arise, which require surgical removal, such as an enlarged pseudocyst that may lead to narrowing of the main pancreatic duct or cause traffic occlusion there. In addition, sometimes pseudocysts may also appear in chronic pancreatitis, but they are often multiple and take a long time to form, so they are not easily detected.