In order to improve catalytic activity, increase recycling times, reduce use cost for enzyme, superpara- magnetic carboxymethyl chitosan/sodium alginate nanosphere (SM/CMC/SA) has been synthesized via an improved hydrothermal method, molecular self-assembly technology, electrostatic interaction and amide linkage. Its mean diameter was 65nm, zeta potential was −36.9mV and BET was 53.8m2/g. -Amylase was selected as a simulation object to manufacture an immobilized enzyme (SM/CMC/CA/ - Amy), and its catalytic activity, release behavior, reusability and stability were researched. Immobilization increased 4.67 times to catalytic activity, slowed down release rate and improved reusable performance. SM/CMC/CA/ -Amy showed higher activity over a wider pH range, especially in strong acidic and alka- line environments. The thermal stability and storage stability were improved remarkably too. All these results indicated that SM/CMC/SA was an ideal carrier for immobilizing enzyme.