In order to better evaluate shale oil and gas resource potential in Nanpu Sag, the paper integrated use of geological and geophysical data, cores and flakes observing, electron microscopy scanning, X diffraction mineral analysis and other experimental methods, fracture characteristics and influencing factors in Nanpu Sag shale reservoirs were studied. It has shown that: fractures in shale reservoir can be classified into four types: structural fracture, abnormally pressurized fracture, diagenetic shrinkage fracture and micro-layer between layers, among which high-angle structural fracture is the main type. Pore types, complicated pore structure and various combination forms, including: organic pores, intergranular pores and intragranular pores. There are four main aspects affecting the forming mechanism of shale fracture, sedimentation, tectonism, formation overpressure and diagenesis. Tectonism controls the number and distribution of fracture development, which is the main factor in Nanpu 1st, 2nd and 5th tectonic belt, and Gaoliu region.