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The correlations between fiber dispersion and physical properties of chrome tanned leather were investigated to provide new insights into improving leather quality and designing tanning agents and tannages. Wet blues were prepared by tanning pickled pelts with different amounts of chrome powder, and their pore structures in the range of 5.48 nm–120 μm were measured using a mercury intrusion porosimetry (MIP). The porosity and total pore area of wet blue increased with increasing amount of chrome powder from 2% to 8%. These MIP data combined with the images observed using a field emission scanning electron microscopy and a scanning transmission electron microscopy–energy dispersive spectroscopy indicated that chrome tanning agent opened up the microfibrils, fibrils, elementary fibers and fiber bundles of wet blue. The sufficient fiber dispersion of wet blue was attributed to the fact that chrome tanning agent penetrated into the microfibrils and fixed collagen fibers from microfibril level to fiber bundle level. The wet blues were then fatliquored to prepare crust leathers. The tensile strength, tear strength, elongation at break, softness, fullness and water vapor permeability of the leathers improved with increasing chrome powder. These results implied that there is a positive correlation between fiber dispersion and physical properties of chrome tanned leather.