Abstract: The design of enzyme-carrier complexes with high stability and selectivity is the focus of research in the field of immobilized enzymes. In this study, magnetic nanoparticles were prepared by precipitation using epichlorohydrin as surfactant and coated with chitosan to immobilize cellulase. Scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectrometer (FTIR infrared spectroscopy) were used to characterize Fe₃O₄ chitosan magnetic nanoparticles, and the characterization and enzymatic properties of immobilized cellulase were studied. Results showed that the prepared magnetic nanoparticles were crystallographically intact and the cellulase was effectively immobilized on the Fe₃O₄-chitosan carrier surface. In addition, immobilised cellulase had better acid-base stability and thermal stability than free cellulase. It had good activity in the range of pH2~9, and also with better thermostability, remained nearly 50% activity for 4 h at 60 and 70 ℃. After 10 cycles of recycling, the immobilized cellulase remained at a high activity of 52.6%, indicating that Fe₃O₄-chitosan could be used as an effective carrier for immobilized cellulase, providing a reference for further applications of the immobilized enzyme.