EUS is a component of intracavitary ultrasound, and the ultrasound probe is small because it enters the body. Conventional ultrasound gastroscopy is performed with a probe placed at the end of the endoscope with an external water bladder, which is filled with airless water and can be directly explored, with a probe diameter of about 10 mm. Another type of probe is the one that extends from the endoscopic biopsy clamp channel to the target organ, so the diameter is only 1.8-2.4 mm, this kind of ultrasound gastroscope is actually an ultrasound probe, also called transendoscopic ultrasound microprobe, because this kind of probe can carry out ultrasound investigation of small ducts such as bile and pancreatic ducts, so it is also called intraluminal ultrasound, conventional EUS ultrasound frequency is usually 7.5-12 MHz, mainly used for gastrointestinal tract (such as stomach, colon) and adjacent It is mainly used for the examination of the gastrointestinal tract (e.g. stomach, colon) and adjacent organs. The Department of Gastroenterology at our hospital has two types of ultrasound endoscopes with two probes. The ultrasound endoscopy technique can observe the origin, depth of infiltration, and adjacent lymph nodes of the gastrointestinal tract lesions, which helps to identify the benign and malignant nature of the lesions and the TNM stage of the tumors, providing an important tool for the diagnosis and treatment of gastrointestinal diseases.