Abstract: In order to reveal the complicated pore structure characterisitcs of tight sandstone, this paper made a quantitative study of the tight sandstone sample from the Chang?7 member of Yanchang formation in Ordos basin by high?resolution CT scanning system, obtained the high?accuracy 2D and 3D pore throad images of it by using CT threshold differences, developed the tigh sandstone pore network model using digital core method, and conducted quantitative parameter statistics and analysis from this model, obtaining the radius distribution of pores and throats and their contributions and pore throat connectivity characterisitcs to the tight sandstone storage spaces, hence realizing the quantitative characterization of micro?pore structures of the tight sandstone. The results show that the tight sandstone of Chang?7 member of Yanchang formation in Ordos basin is characterized by continued distribution of micron pore throats, different contributions of different radius pores to the storage spaces, of which the pores with radius over 2 μm are the main storage spaces of it, and a certain connectivity between pores and throats, with coordination number from 1 to 3