Abstract: To improve the separation efficiency of thermo-sensitive poly(N-isopropylacrylamide) (PNIPA) hydrogels, an inverse suspension polymerization process was used to prepare PNIPA hydrogels by using ammonium persulfate and N,N,N′,N′-tetramethylethylenediamine as a pair of redox initiators, and N,N′-methylene bisacrylamide (BIS) and divinylbenzene (DVB) as the multiple crosslinking agents. The morphology, thermo-sensitivity and the application to the separation of poly(ethylene oxide) glycol (PEG) aqueous solution of the resultant PNIPA hydrogels were investigated. It was found that the obtained hydrogels were in the form of beads with a rather compact structure and had a lower critical solution temperature (LCST) of 32℃. The separation efficiency increased with the increase of the molecular mass or with the decrease of the concentration of PEG. Increasing the amount of crosslinking agents could also improve the separation efficiency, and the introduction of hydrophobic DVB was an effective way to improve the separation efficiency without the loss of swelling ratio of hydrogels.