In order to reveal the preparation mechanism of dextran-ovomucoid affinity ultrafiltration carrier and evaluate the application effect of the carrier,first,dextran T2000 ( dextran with a relative molecular mass of 2 × 106 ) was employed to synthesize a water-soluble affinity carrier after the epichlorohydrin activation,with ovomucoid as the affinity ligand. Then,the changes of infrared adsorption spectrum and ultraviolet adsorption spectrum of the affinity carrier during the preparation were investigated,and pilot study on trypsin purified by the affinity ultrafiltration was performed. The results show that the activation of dextran can be described as a bimolecular nucleophilic substitution ( SN2) process,that the adsorption isotherm of trypsin by dextran-ovomucoid carrier can be described by the Langmuir isotherm equation,that the purification factor and the activity recovery rate respectively reach 45 times and 80%,and that the affinity of the carrier to trypsin is of high specificity,which may result in excellent purification effect of trypsin by affinity ultrafiltration.