The research was to design a carrier used in tissue engineering and drug-release system. In this article, a new dispersion polymerization system without organic solvent was described to prepare poly(ethylene glycol) diacrylate/2-hydroxyethyl methacrylate (PEG-DA/HEMA) copolymer hydrogel microspheres as carrier, which introduced chitosan (CS) as reaction medium and costabilizer, polyvinylpyrrolidone (PVP) as steric stabilizer and benzoy peroxide (BPO) as initiator. The effects of mass ratios of monomers, concentration of stabilizer and initiator on partilcle size and polydispersity index (PDI) of microspheres were investigated. Furthermore, bovine serum albumin (BSA) as protein model, the composition of copolymer, size, and polydispersity index of microspheres were employed to study the amount and released ratio of loaded BSA in this article. The results showed that hydrogel microspheres with 3.26 +/- 0.24 mu m in particle size and 1.03 +/- 0.008 in PDI, obtained with mass ratios of PEG-DA 60/HEMA 40, 2 wt % of stabilizer content and 2 wt % of initiator content (relative to total mass of monomers), had 124.57 +/- 3.14 mg/g in the amount of loaded BSA and 59.09 +/- 1.43% of released ratio. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012