One γ ray spectrum analysis method is introduced in the paper. A spectrum composed of different compo- nents is analyzed by considering the branching ratios of various γ rays from the same nuclide and the relative detec- tion efficiencies to get the optimized results. The function of describing the background of the γ-ray spectrum is also given. With this method to determine contents of various radioactive nuclides

some analysis steps can be merged and the measurement error will be reduced.