A simple two-step aqueous polymerization method was introduced to synthesize polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. The sorption behaviors and mechanism were studied by the sorption of PAC/PEG IPN hydrogel to Fe3+ ion from aqueous solution. The experimental results revealed that the adsoption amount of Fe3+ ion using swollen hydrogels was much higher than that using the dried composite, they were 75.69 mg/g and 14.25 mg/g, respectively. The parameters, such as neutralization degree, acrylic acid (AA) dosages and temperature, on the sorption amount of PAC/PEG IPN hydrogel were detailedly investigated.