Abstract: The optimal resolution determination method of micro-computed tomography (Micro-CT) scanning was presented here based on two-dimensional slices at different resolutions for ideal unit cell model, and the meso-structure and permeability of 3K 5-harness satin woven fabric were characterized based on the CT image at the optimal resolution. Firstly, the ideal unit cell model of the fabric was converted into 2D slices at different resolutions and the effects of resolution on the characterization of cell structure and permeability were investigated. Thereafter, the optimal resolution was determined for fabric CT scanning. Then, the CT image of the fabric with the optimal resolution was used for the meso-structure and through-thickness permeability characterizations of the fabric. The results show that the optimal resolution for the CT scanning of 5-harness satin woven fabric is 15 μm. The path and cross-sectional variation of the yarns in the fabric can be obtained by Micro-CT accurately. The inter-tow voids of the multilayer fabric are arranged periodically along the three main directions with an average inter-tow porosity of 16.6%. The through-thickness permeabilities obtained based on Micro-CT are in good agreement with experimental results.