Abstract: In γ spectrum analysis for the sample with a certain geometrical size, the γ-ray self-absorption affects accurate calculation of radionuclide. In this paper, the main calculation methods of self-absorption correction factor at home and abroad were compared, and the defect of the simplified calculation model and effect on measurement result were analyzed. The accurate calculation model for self-absorption correction factor was established based on hybrid Monte Carlo simulation method. The random sampling and integral calculation were done using FORTRAN program, and the accurate self-absorption correction factor was obtained. Through the experimental measurement of spiked samples and different quality standards, the accurate calculation model was compared with the result of simplified calculation model and source-less calibration software. The results show that the self-absorption correction factor evaluation of simplified calculation model is less than that of the experimental measurement results, but the calculation result of accurate calculation model is in agreement with the results of experimental measurement and source-less calibration software, and the relative deviation is not more than 5%. For the key radionuclides around nuclear power plant, the self-absorption correction factor of soil was calculated by accurate calculation model.