Abstract: Micro CT is usually used at atmospheric pressure, leading to the pore throat characteristics obtained under the actual overburden pressure different from those obtained from CT scanning. In order to make the CDRM’s pore throat structure more similar to the actual one, taking the porosity and permeability data under overburden pressure from tight sandstones of the second and third member of Qingshankou formation in Longhupao area, Songliao basin as examples, the paper studies the influences of the overburden pressure on porosity and permeability. Combined with Micro CT scanning images and dilation algorithm, the variations of porosity and permeability of a digital core under the overburden pressure are simulated and a digital core model corrected with overburden pressure is established on the basis of overburden pressure exponential function and dilation algorithm. The results show that the pore space in the digital core is reduced obviously, and the simulated permeability obtained from the corrected digital core model is consistent with the calculated value of overburden permeability test with the coincidence rate over 90%. Compared with the traditional CDRM, this model can reflect the characteristics of pore throats under the condition of overburden pressure and provide guidance for oil and gas development