Abstract: Porous materials with good mechanical properties were prepared using kapok fibers and polyethylene terephthalate fibers (ES) as raw materials through freeze-drying and hot-air bonding processes, and these materials were used as a framework to reinforce sodium polyacrylate hydrogels. The microstructure, mechanical properties, and swelling behavior were investigated. The results showed that kapok/ES porous materials exhibited good moldability and excellent mechanical properties. Reinforcing sodium polyacrylate hydrogel with kapok/ES porous materials significantly improved the mechanical performance and swelling behavior of the hydrogel. The swelling processes of pure sodium polyacrylate hydrogel and kapok/ES porous material-reinforced hydrogels were studied using the Korsmeyer-Peppas model and the pseudo-second-order kinetic model, respectively. It was found that the Korsmeyer-Peppas model was more suitable for pure sodium polyacrylate hydrogel, while the pseudo-second-order kinetic model was more suitable for the kapok/ES porous material-reinforced hydrogel. The theoretical equilibrium swelling ratio S_∞ was consistent with the experimental results, and as the concentration of NaCl solution increased, the experimental S_∞ values became closer to the theoretical values.