Abstract: The effective porosity has an important significance for the study of porous media liquid.Therefore,in order to determinate it,it is particularly important to explore new accurate methods.An approach of calculating effective porosity by the combination of three-dimensional laser scanning and gas displacement method(3DLS-GD)was proposed in this research.The volume of the core can be obtained through3 DLS,and the effective porosity can be acquired by utilizing Helium displacement method.Experiments show that volume calculated by 3DLS is more accurate than the default volume,and it can reduce the error of 3.92%.Scanned volume and surface area increase with the enlargement of the scanning resolution.The effective porosity calculated by 3DLS-GD method is closer to the actual situation than the results calculated by default volume,and it can reduce the error of 16.550 3%,43.232 6%in sand samples.