AbstractChanges of the pore structure of recycled fibers and the strength properties of papers produced by old corrugated container (OCC) recycled fibers were studied, after they were subjected to different stock preparation and papermaking processes. In this paper, the effects of beating, sizing, pressing, and drying on fiber properties were investigated, and the porous structure of fibers was analyzed by nitrogen adsorption technique. The results showed that beating, pressing, and other physical processes significantly influenced the fiber properties, whereas sizing were . Significant changes of water retention value (WRV), crystallinity index, and paper strength were observed after those processes. Further, an effort has been made to show relationships between pore structure and macroscopic properties (WRV, crystallinity index) of recycled fibers.