Abstract: It is too expensive and time consuming by use X-ray computerized tomography（CT）to obtain the real 3D digital
cores for representing the true microstructures of rocks. It is important in both theory and applications to reconstruct 3D
digital cores based on 2D thin section of rocks and evaluate the accuracy of reconstructed digital cores. 3D digital core was
reconstructed utilizing petrographical information obtained from two dimensional thin sections to model the results of the main
sedimentary rocks forming processes-sedimentation，compaction，and diagenesis. The accuracy of this method is evaluated
by calculating local porosity distribution function and average percolation probability function in real 3D digital cores and the
reconstructed digital cores. The results show that the homogeneity and connectivity of reconstructed three-dimension digital
core by process-based method are similar to those of true 3D digital core and both of the reconstructed 3D digital core and true
3D digital core are isotropic. Reconstruction of 3D digital cores can be used to characterize the pore structure of the true core，
and can also be used as the basis for simulation of other physical properties.

Key words: 3D digital core, process-based method, local porosity distribution function, average percolation probability function, 2D thin section