Abstract: The pore structure of the low permeability sandstone reservoir is complex and has strong heterogeneity in two-dimensional and three-dimensional space, and it has a dramatic effect on logging response of reservoir. However, the mercury intrusion curves, NMR T₂ spectrum and thin section three kinds of data each reflects the different characteristics of the pore structure in some way. In this paper, the microscopic pore structure parameters of three kinds of data were extracted for correlation analysis, finally, pore structure classification was achieved respectively by PCA-FCM, and the classification result is consistent with the mercury intrusion curve fractal method.