Abstract: The beam hardening can be depressed in liquid detection by dual-energy CT based on projection decomposition. However, the calculation error of effective atomic number is still very obvious if the container’s material is high density metal. Under the frame of dual-energy CT pre-reconstruction, a linear correction method for the calculation result of electric density and effective atomic number of the liquid in high density cylindrical containers was proposed according to experimental data analysis in this paper. The presented method can improve the calculation accuracy of effective atomic number substantially. And this method is also suitable for the situation that several containers are inspected together. The experimental results indicate that the method is valid.