Dialdehyde oxycellulose was prepared as carrier to immobilize the β-galactosidase.The preparation conditions,microstructure and enzymatic properties of the immobilized enzyme were studied.The results showed that the maximum activity of immobilized enzyme is 0.517U/g when immobilized time is 4h,[enzyme]∶[carrier] =1∶15(g∶g).The microstructure of immobilized enzyme,which was studied with infrared spectrum and scanning electron microscope analysis,showed that the aldehyde group of dialdehyde oxycellulose could react with the amino group of the β-galactosidase to form immobilized enzyme.Compared with free enzyme,the heat stability and acid as well as basic resistance of immobilized β-galactosidase were increased;the decrease of the affinity with substance of dialdehyde oxycellulose immobilized β-galactosidase was demonstrated by michaelis equation analysis.After reuse for five times,the relative enzyme activity of immobilized enzyme was 63%.