The invention provides a digital core constructing method and device. The method comprises the steps of simulating an actual core sedimentation process; replacing a preset proportion of rock particles with potassium feldspar; performing secondary enlargement and compaction on the rock particles to obtain a digital core with a simulated genetic porosity; filling a preset volume of clay into the digital core with the simulated genetic porosity; setting a porosity of the filled digital core as a preset value, adjusting a proportion between macro pores and fine pores in the filled digital core to a preset value, keeping the porosity as the preset value and obtaining the constructed digital core. By means of all embodiments of the invention, the validity and the reliability of rock physical characteristics obtained through simulation can be effectively improved.