Abstract: Taking the sandy conglomerate reservoir of Baikouquan formation in Mahu sag as the study objects, micro-CT scanning technology is used to investigate the characteristics of the 2D and 3D pore structures of the rock in the sandy conglomerate reservoir. The results indicated that the sandy conglomerate sample obtained from Baikouquan formation in Mahu sag is dominated by residual intergranular pores, dissolved pores and micro-cracks. The shapes of the pores are irregular, the pore throats are of different sizes and their distributions are mainly contiguous and isolated; microscopic heterogeneous pore distribution is noted and even obvious in the samples with poor physical properties; equivalent pore radius is mainly in unimodal distribution and mostly less than 50 μm, and the proportion of small pores in the samples with relatively poor physical properties is higher than that in the samples with good physical properties