The imaging of small nerves plays an important role in clinical diagnosis and treatment, and the traditional imaging techniques are difficult to visualize small nerves. the advancement of ultrasound technology and the increasing resolution of ultrasound imaging equipment made it possible to observe some small nerves. The Anatomy of these small nerves can provide guidance for nerve block. In addition, the changes in cross-sectional area of the nerve, sonogram and Doppler signals are common manifestations of various diseases and can be used as a basis for diagnosis and evaluation of treatment. The aim of this review is to provide timely update about the current status and development of the application of high-frequency ultrasound technology for various small nerve imaging, related diagnosis and nerve block.