Objective To improve the bonding ability between carbon fiber and matrix resin. Methods The surface of carbon fiber was modified by chemical grafting of PMMA. First, mixed acids of nitric acid and sulfuric acid were used to pretreat the carbon fiber, leading to the formation of reactive functional groups on the surface, and then benzoyl peroxide (BPO) was used as the initiator and methyl methacrylate (MMA) as the monomers to realize polymerization by the suspension method. The carbon fiber samples before and after treatment were characterized by FT-IR,TG, SEM and XPS analyses. Results Streching vibration characteristic peaks of carbonyl groups appeared at 1775. 28 cm-1 in the infrared spectra of grafted carbon fiber. The thermal weight loss rate was 6. 08% after grafting, which was about 5% more than those of untreated sample and mixed acid treated samples. The surface morphology showed that PMMA existed in local regions on the surface of the carbon fiber. XPS result revealed that there were more oxygen containing groups on the surface of carbon fiber after chemical grafting. Conclusion The method enabled MMA polymerization on the surface of carbon fiber, in the form of grafting chemical bond on the surface of carbon fiber.