Abstract: This paper used eddy current testing technology, adopted encircling coil by differential coil method to implement eddy current testing of NbTi/Cu hexagonal single-core bar. The results showed that eddy current inspection could effectively detect defects of inclusion, compression injury, knock injury, and so on in the Cu surface layer of the single-core bar. The eddy current testing could ensure the quality of NbTi/Cu hexagonal single-core bar and the quality of NbTi/Cu superconducting wire could be better controlled.