Abstract: Cladding material is the focus in the fuel assembly design, and the main characteristics that limit the cladding material is its corrosion performance. The corrosion mechanisms in zirconium alloys is complicated, and the neutron irradiation condition causes uncertain effects on the corrosion of zirconium alloys, and thus, it is difficult to estimate the zirconium alloy corrosion behavior and build the corrosion model just based on the out-pile corrosion test. In this paper, the corrosion model is built for the first time by analyzing the in-pile corrosion test results for Zr-1Sn-1Nb-0.3Fe.