Abstract: The distribution of reservoir fractures in Damintun sag in Liaohe field is quantitatively predicted by analysis of the regional tectonic stress field feature and establishment of rational geologic and mechanical model in this study area based on finite element approach.Through 3D tectonic stress field numerical simulation and analysis, the distribution diagram of the first, second and third principle stresses and the maximum shear stress in the Archeozoic reservoirs in the buried hill are obtained. And the composite fracture density value (β) is given based on rupture value (I) and energy value (u) evaluation indices. The case study shows that the fracture density predicted by using βindex is more identical with statistical density of cores fracture from drilled wells. Comparing with previous single evaluation index, the accuracy of fracture prediction is greatly increased