The mediastinum location is anatomically deep, surrounded by bony thoracic and lung tissue. Ultrasound was thought to be not suitable for the examination of mediastinal tumors. However, as the development of technical equipment and ultrasound research on the diagnosis of mediastinal tumors, more and more new ultrasound techniques play an important role in the diagnosis of mediastinal tumors, and new techniques applying to children are more stricter than that of adults. This article reviews the application status of ultrasound technology in mediastinal tumors of children.