Abstract: The low-permeability sandstone reservoir of Toutunhe formation in Wellblock Shinan-21 of Junggar basin is characterized by strong heterogeneity and great physical property differences in profile. Based on physical property analysis and the data of mercury injection and casting thin section, regarding microscopic pore-throat structures of the reservoir, the reservoir can be divided into 4 types through parameter optimization by using cluster analysis method. The Toutunhe formation in Wellblock Shinan-21 is dominated by Type Ⅱ and Type Ⅲ reservoirs that are mainly influenced by shale content. The larger the shale content is, the poorer the pore structure and the lower the permeability will be. The error of permeability of shaly sandstone reservoir interpreted with conventional model is relatively large. According to shale content and combining with reservoir classification, the paper establishes 4 permeability interpretation models for the 4 types of reservoirs, respectively. The actual application shows that the new models can well match with core analysis data, the interpretation accuracy is improved by 7.8% compared with that of the conventional model and good effects have been gained, which can be widely used for other low-permeability shaly sandstone reservoirs