Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers in mixed solvents of dioxane and water was studied. The factors affecting the grafting reaction, such as solvents composition, reaction time, temperature, pH of reaction media, concentration of acrylamide and hydrogen peroxide were examined. The modified fiber was characterized with IR, scanning electron microscopy (SEM), elemental analysis, XPS, contact angle measurement and the grafting yield. The O/C ratio and N/C ratio on the surface increased after treatment and the surface of the Kevlar fiber became rougher. The contact angle decreased from 80 to 45 after grafting, indicating the wettability of the fiber increased after modification. All the results suggested that AM have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. And the probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface was proposed.