Starch based graft copolymers have been researched due to their useful properties such as environmentally friendly and biodegradable characteristics in plastic industry, easy handling better than other carbohydrates etc. In this study, starch based graft copolymers with carboxylic acrylate monomer were prepared by reactive extrusion in a twin screw extruder. The monomers were reacted with corn starch under various conditions in the extruder with ammonium persulfate (APS) and potassium persulfate (KPS) as initiators and the mixture of penthaerythritol triacrylate and pentaerythritol tetraacrylate (PETIA) as the cross-linking agents. The effects of various parameters such as the amount of initiator added, feeding rate, reaction temperature and reaction time on graft efficiency were also investigated. The graft copolymers could be verified using fourier transform infrared spectroscopy (FT-IR). To analyze the graft efficiency in detail, nuclear magnetic resonance (NMR) was also measured. And the uniformity of graft reaction was verified using scanning electron microscopy (SEM).