Abstract: Magnetic Fe3O4 was synthesized by chemical coprecipitation. PDDA with positive charge was adsorbed on the surface of Fe3O4 forming PDDA-Fe3O4 composites. In order to improve the stability and repeating utilization factor of glucose oxidase, glucose oxidase was immobilized on the self-made magnetic PDDA-Fe3O4 carrier via electrostatic interaction. The results showed that the average size and Zeta potential of PDDA-Fe3O4 particle were 275 d.nm and 47.6 mV. The optimal immobilization conditions were as follows: temperature 15℃，pH=6，the mass ratio of enzyme and carrier was 15mg/g. The thermal stability, pH stability and operational stability of the immobilized enzyme were all improved greatly.

Key words: magnetic carrier, glucose oxidase, immobilization, property