Abstract: The research of microcosmic mechanism and geologic origin of low-resistivity layers in continental reservoir of Jiyang Depression showed that microcosmic factors for reducing apparent resistivity of oil layer included mainly high-salinity formation water of reservoir, additive conductivity of shale in reservoir and development of fine pores of reservoir. In order to determine the electric conductivity of matrix in some electric conductive minerals, the resistivity of some dry cores in this area were measured. The results of experiment showed that electric conductive minerals were not enough to form matrix electric conduction network independently and could not show extremely electric conductive property. Therefore their influence on the resistance of reservoir was very weak. The formation of low-resistivity layers was closely related to sedimentary system, sediment sources and its evolvement, diagenesis and structural faults. The favorable development zones of low-resistivity layers are mainly the reservoirs in the sedimentary environment of drought salted lake basin, the reservoir upwards 1000 meters of basin edge, the slump fan of the delta front, the deepwater turbidite fan and steep slope fan front of base of middle Es₃, top of Es₃ and base of Es₂, reservoir of Es₃ and Es₂ nearby faults and capable of trapping high-salinity formation water of deeper layer.