Abstract: In order to study the applicability of array eddy current technology in the online detection of nuclear fuel cladding tubes, the array eddy current testing equipment was used to verify its detection ability of artificial defect contrast tubes. The test results show that the artificial defects such as ϕ 0. 2 mm through hole, the inter and outer wall defects of depth of 10% of wall thickness, width of 0. 2 mm, length of 3 mm and so on can be accurately identified within 0. 55 mm wall thickness range of nuclear fuel cladding tube.