Abstract: This paper studies the micro forming mechanism of the low resistivity reservoirs in the J oilfield, based on the data of x-ray thin cast section, formation water, overburden pressure corrected porosity and permeability, grain size, sensitivity and oil testing. The data shows that the micro forming mechanism of low resistivity reservoir in the J oilfield is mainly related to the occurrence of clay minerals and micro pore fractures, wetness and particle size. The mineralization of formation water also has certain influence on the formation of low resistivity reservoirs.