Abstract: γ-ray absorption coefficient in different materials, such as Pb, Cu and Al, are measured by γ-ray energy spectrum analysis. The results are 1.213, 0.642 and 0.194 cm~(-1), respectively, and the relative difference is about 1% compared with the value of generally acknowledged for ~(137)Cs energy spectrum. The results are 0.674,0.481 and 0.149 cm~(-1), respectively, and the relative difference is less than 5% for ()~(60)Co energy spectrum. The task of thickness measurement of Fe are performed by known absorption coefficient. The relative difference is within 2.5% for ~(137)Cs γ-ray energy spectrum.