A semi-interpenetration (semi-IPN) superabsorbent polymer (SL-g-P(AA-AM)/PVP) was synthesized by using sodium lignosulfonate (SL), acrylic acid (AA), acrylamide (AM) and polyvinylpyrrolidone (PVP) as raw materials, potassium persulfate (KPS) as initiator and N, N′-methylene bisacrylamide (MBA) as cross-linking agent. The effects of hydrolysis time, hydrolysis concentration, hydrolysis temperature and stirring rate on water absorption of resin were investigated by single factor optimization experiment. The structure, thermal stability and surface morphology of samples before and after hydrolysis were investigated by FTIR, LNMR, XRD, TG and SEM. The swelling, water retention and reusability of samples before and after hydrolysis were evaluated. The results showed that the resin obtained by hydrolysis under the condition of NaOH concentration of 0.0125 mol/L, hydrolysis temperature of 75 °C and stirring rate of 400 r/min for 2 h had a water absorption rate of 2011.12 g/g, which was substantially higher than that of the unhydrolyzed resin (1292.11 g/g). The swelling behavior of the resin before and after hydrolysis was complied with the first-order and second-order swelling kinetic models. The swelling ability of H-SL-g-P(AA-AM)/PVP in NaCl solution with a mass fraction of 0.9% (123.65 g/g) was higher than that of SL-g-P(AA-AM)/PVP (97.41 g/g), but the swelling ability in MgCl₂ and FeCl₃ solutions was not improved due to the increase of -COO^_- after hydrolysis. The swelling ability of H-SL-g-P(AA-AM)/PVP was greatly affected by the pH of solutions. Furthermore, the water retention performance of hydrolyzed resin was superior to that of unhydrolyzed resin, and it exhibited certain reusability.