In this paper， magnetic nanoparticles Fe3O4-SiO₂-HPG-COOH was prepared as immobilized carrier to covalently immobilize horseradish peroxidase (HRP)， and applied to the degradation of zearalenone (ZEN). The immobilized HRP was characterized by Fourier transform infrared spectroscopy， X-ray diffraction and scanning electron microscopy， which verified that HRP was successfully immobilized on the carrier. The prepared nanoscale carrier Fe3O4-SiO₂-HPG-COOH has uniform size and shape， good dispersion and strong magnetic properties. The saturation magnetization value was 25.80 emu/g， and the average particle size was 103.15 nm. Compared with free enzyme， the magnetically immobilized HRP indicated higher acid-base tolerance and thermal stability， the optimal pH value was increased from 6.5 to 7.0， the optimal temperature was increased from 30 ℃ to 35 ℃. Magnetic immobilized HRP was applied to ZEN degradation， and the relationship between solution pH， reaction temperature， hydrogen peroxide concentration and reaction time with ZEN degradation rate was investigated using single-factor experiments. The results showed that under the conditions of reaction temperature of 35 ℃， hydrogen peroxide concentration of solution 26 mmol/L， pH 7.0 and reaction time 480 min， the removal efficiency of ZEN was 68%. The immobilized HRP had good repeatability， and the relative enzyme activity remained above 79.85% after 5 cycles. This research shows that magnetic immobilized HRP has good degradation ability to ZEN.