Abstract: A novel modified poly (aspartic acid)/poly (acrylic acid) composite absorbent resin was prepared with Acrylic acid (AA) as the monomer, potassium persulfate (KPS) as the initiator and modified poly (aspartic acid) (MKPAsp) as the crosslinking agent in an aqueous system. The absorbent resin was characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). SEM confirmed that the introduction of PAA into the network structure can optimize the pore channel structure, increase the pore density and make the pore sizes become uniform. The swelling properties of the composite resin in different temperature, pH and salt solutions were investigated in this study, the results showed that the LCST of MKPAsp/PAA composite absorbent resin was10℃ high than that of KPAsp, which suggested that MKPAsp/PAA composite absorbent resin had a better temperature sensitivity. The composite absorbent resin had the best swelling ratios at pH=6 and 10; the salt tolerance of the composite resin was significantly enhanced and the absorbency order in different chloride salt solutions was: Na > Fe3 > Ca2 . The optimum swelling ratios of the prepared MKPAsp/PAA composite absorbent resin in distilledwater and 90 mmol/L NaCl solution were 886.7g/g and 165.1g/g respectively, which were enhanced by 3.9 and 2.3 times than that of KPAsp resin.