Abstract: The determination method of 237 Np in the large amount of uranium by γ spectrum is developed. Based on the γ radiation peak at about 86 keV of 237 Np, eliminating the influence of its daughter species 233 Pa, 237 Np can be determined quantitatively by γ spectrum. Large amount of uranium contained in the solution strongly absorb the γ ray of about 86 keV, but the logarithm of the peak area has linear relationship with the uranium concentration. Filling this relationship by the way of least square method, the absorption effect of uranium can be corrected, and then the 237 Np can be directly determined in uranium solution by γ spectrum.