Abstract: The shale oil reservoir of the first member of Paleogene Shahejie Formation（Es1）is the focus of future exploration in the Nanpu Sag of Huanghua Depression. The petrological characteristics，reservoir space types and pore structure characteristics of shale reservoir of Es1 in Nanpu Sag were studied by means of core and thin section observation，scanning electron microscope，nuclear magnetic resonance and X-ray diffraction. The results show that： （1）Four lithofacies are developed in the shale of this area，including gray and dark alternating horizontal laminar felsic shale，dark gray massive mixed shale，gray graded laminated mixed shale，black gray horizontal laminar mixed shale. Shale oil is mainly stored in dark gray massive mixed shale，gray graded laminated mixed shale，black gray horizontal laminar mixed shale.（2）The black gray horizontal laminar mixed shale has the most developed fractures and the largest porosity，and the gray graded laminated mixed shale has higher porosity and less fractures than the dark gray massive mixed shale. The reservoir space includes fractures，residual intergranular pores，mineral intercrystalline pores and dissolved pores. The pore throat is characterized by large pores and tiny throats，the pore radius ranges from 125.369 μm to 156.048 μm with an average of 133.209 μm，and the throat radius ranges from 0.377 μm to 0.860 μm，with an average of 0.622 μm.（3）The mixed shale of Es1 in Nanpu Sag has a large thickness，good oil-bearing properties，developed fractures and good reservoir performance. It has good shale oil formation conditions and great shale oil exploration potential.

Key words: shale reservoir, reservoir characteristics, pore structures, the first member of Shahejie Formation, Paleogene, Nanpu Sag, Huanghua Depression