This paper presents the novel monosized resins with hydrophilic surface coated polysaccharides

including synthesis of the matrix beads．modification of the particle surface and characterization of HPLC properties of the modified products．The monosized matrix beads based on poly(methyl methacrylate-co-divinylbenzene)(PMMA-DVB) were synthesized by seed swelling polymerization．The linear polystyreneparticles as seeds were swollen by an emulsifying mixture of monomer

crom-linker and initiator in the aqueous solution containing stabilizer at the room temperature

then the swelling products were polymerizedin the same solution system at 70℃．finally the polymerization products were fully washed with water．The particle parameters and apparent morphology of the matrix beads were characterized by scanning electronmicroscopy(SEM)．The results show that the polymerization method is suitable to the preparation of monosized PMMA-DVB beads with particle diameters of 5～15μm

the particle dispersion coefficient of the polymerization products with different cross-linking densities is less than 2％．After being hydmlyzed with a 30％(W／V) NaOH solution at 80℃

the PMMA-DVB beads were transformed into the hydrolyzed resins contmning carboxylic groups on the particle surface．Dextran and DEAE-Dextran were coated respectively by the impregnation method

and then were cross-linked respectively with 1

4-butanedol diglycidyl ether as cross-linker Two new modified resins with covering layer of cross-linked polysaccharides on the particle SUrface were obtained The polyasccharides content of the modified resins was aboUt 7％(W／W) of the matrix beads．In order to get a uniform covering layer

the coating and cross-linking process was generally divided into two or three times to accomplish with same operation method SEM observation showed that the physical morphology of the two modified resins still kept monodisperse particle as matrix beads．Owing to highly cross-linking network structure

the modified resins exhibit good physical and chemical stability．The particles can withstand high pressure operation

can be treated with acidic and alkaline solutions(pH=1～14)．Monodisperse particle size

good particlerigidity andthe surface coated bypolysaccharidesmakethe modified resins as HPLC packings possessing high column efficiency．high permeability and excellenthydrophilic properties．The experiments show that on chromatographic columns packed with the two modified resins

human serum albumin possesses good elution behavior in elution system of phosphate buffer(pH=3.8)

the protein recovery is over 97％ and 99％respectively．