Objective To depict the high-frequency ultrasound imaging of the median nerve of the upper limb in the normal living subject,master the median nerve scanning technique for the measurement of its cross-sectional area (CSA) at 5 easily-identified anatomical sites, reveal its relationship with surrounding tissues,and provide the reference range for clinical diagnosis of peripheral nerve diseases. Methods In 240 healthy volunteers, the CSA of the median nerve were measured by using high-frequency ultrasound at 5 sites which were the carpal tunnel ［rasceta］, forearm midpoint, the point where the nerve passed through the pronator teres, supracondylar humerus and at the midpoint of the humerus. At each site, the measurement was repeated 3 times. The average values of the measurements were analyzed for the correlation between the CSA and height and weight. Results High frequency ultrasound showed that the normal median nerve cross section appeared as a reticular low echo image in a round, oval or triangular shape, whereas its longitudinal section appeared as several parallel low echo bundles with intermittent banded echo segmentation.The CSA of the median nerve at these 5 loci were (10.67±0.94) mm², (10.25±0.61) mm², (9.83±0.50) mm², (11.44±0.43) mm², and (11.24±0.56) mm², respectively. There was statistical significance of the CSAs of the median nerve between humeral supracondylar humerus and the midpoint of the humerus and between men and women. Conclusion The display rate of the median nerve in the high-frequency ultrasound probe and the whole process is 100%. There are differences of the CSA in different parts of the median nerve. The CSA of the median nerve is thick in the upper arm and thin in the carpal tunnel and at the forearm.