Abstract: In order to measure fule rod ²³⁵U enrichment uniformity by neutron activation method, the relativity between γ-ray self-absorption correction factor(F) and the mass of samples(m) was studied. HPGe γ spectrometer was used to measure the self-absorption correction factor of the samples. The γ was produced by ¹⁵²Eu + ¹³⁷Cs standard point source and uranium samples with different mass and enrichment, which were contained in the same type of sample boxes and adapted on collimation. After regression analyses to the self-absorption-correction factor(F) and the mass of samples(m), a F-m linear regression equation could be found. Using the self-absorption correction factors obtained from this method to correct the activity, which was measured when the enrichment of simulate samples was analysed by neutron activation analysis, the result’s deviation is less 1‰ than mass spectrometry.