Poly (styrene-co-methacrylic aicd) (PSMAI) nanofibers with carboxyl groups was prepared by a combination of the soap-free emulsion polymerization method and electrospinning technique, which were employed as solid support to immobilized horseradish peroxidase (HRP) enzyme through the amide bond formation between COOH of PSMAI-cell and NH, of HRP molecules. Scanning electron microscopy(SEM) was used to evaluate the morphology and diameter of the nanofibers. Surface carboxyl of these fibers was confirmed by FTIR spectroscopy. The parameters about immobilizing HRP on the PSMAI nanofibers were studied and influence on the activity of the HRP was discussed. This study showed that soap-free emulsion polymerization method is an ideal technology to modify the polystyrene and ultimately achieve enzyme immobilization on electrospun PSMAI nanofibers surface. The immobilized HRP showed better resistance to pH and temperature than that of free form, and the storage stabilities, reusability of immobilized HRPs were significantly improved. Immobilized HRP equipped in biological reactor is applied to treat the polyphenol waste water. The catalytic removal efficiency of inmobilized HRP for removal of o-methoxyphenol (OMP) remained above 80. 2% for 120 mm. Immobilized HRP equipped in biological reactor is applied to treat the phenol waste water.