Abstract: Alpha-amylase was immobilized by encapsulating in hydrogel beads prepared with alginate-carrageenan.Their mobilization conditions and partial properties of immobilized enzyme were investigated.The best efficiency of immobilization could be obtained under the condition that the concentration of alginate was 3.0%、carrageenan was 1.0%、Alpha-amylase was 18g/L and CaC12 was 0.8% and the immobilized enzyme activity was 139.66 U/g·min.The recovery of activity was 55.70%.Compared with the free enzyme, the optimum pH value and temperature of immobilized alpha-amylase were shifted from 7.0 to 6.0 and from 60℃ to 70℃ respectively.It showed a wider range of reaction pH value and temperature than the free enzyme.The thermostability of immobilized alpha-amylase was better than native enzymes.After 5 times repeated batch operations, the relative activity of immobilized enzyme was about 65%, showing a high operational stability.