In recent years, the application of EUS in the diagnosis and treatment has become increasingly popular due to the rapid technological advancements in this field. With the application of new technologies, EUS assistants encounter various problems or “pitfalls” during clinical operations, which may pose challenges to the successful completion of relevant procedures. For example, a needle tip may not be visualized by ultrasonography during EUS-FNA; a stiff fine needle may not be introduced through the working channel of the endoscope in the duodenum, and withdrawal of a guidewire in a needle may be associated with tearing and peeling of the guidewire in EUS-guided biliary drainage. In view of these commonly encountered problems, this article summarizes the countermeasures that EUS assistants can take for EUS-FNA and EUS-guided drainage to improve the efficiency of the procedures and reduce the occurrence of adverse events.