Abstract: CENTER fuel assembly irradiation test should be carried out before the fuel assembly is formally designed, and the CENTER fuel assembly would be irradiated in HFETR to complete the fuel burn-up test. To ensure the success of the irradiation test and meet the test requirements, the accuracy of power calculation and measurement of fuel assembly in the process of irradiation test should be studied. According to the characteristics of CENTER fuel assembly, the mosaic coupling method was studied and determined. The fuel assembly was irradiated in HFETR, and the test is conducted. The difference of the fuel burn-up between calculation and measurement is 3.25%, and the burnup of CENTER fuel assembly irradiation test meets the test requirements.