The immobilization conditions of alginate lyase from Microbulbifer sp. were explored in this study. Tannic acid functionalized magnetic nanoparticles (TA-MNPs) were used as the immobilized carrier to optimize the immobilization conditions of alginate lyase by determining the specific activity and activity recovery of the immobilized enzyme. Then the immobilized enzyme was characterized by Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). When the carrier amount was determined to be 10 mg, the optimized immobilization conditions for the alginate lyase were determined as follows: glutaraldehyde concentration 1.00%, cross-linking time 2 h, immobilization temperature 5 ℃, immobilization time 8 h, immobilization pH 8.00, and enzyme dosage 1.20 U. The immobilization effect was the best under these conditions with the specific activity and activity recovery of 36.56 U/g and 30.55%, respectively. The results of FTIR showed that the alginate lyase was successfully immobilized on the surface of TA-MNPs. The results of TEM showed that TA-MNPs had good dispersion and were regular spherical. After immobilization by TA-MNPs, the immobilized enzyme showed the obvious aggregation and little change in particle size. Compared with the free alginate lyase, the immobilized enzyme enhanced thermal stability, pH stability, and storage stability. Optimization of the immobilization conditions of Microbulbifer sp. alginatelyase laid a good foundation for the preparation and application of the immobilized enzyme.