Carbon fiber epoxy composite are widely used in airframe structures, space vehicles, sports equipment, and high speed reciprocating parts for industrial machinery. In this paper, the groove processing characteristics of carbon fiber epoxy com-posite was experimentally investigated in order to study the endmill operation of fiber reinforce epoxy composites. Followings are main finding from the experimental results. First, the cutting and bending force in groove processing of the carbon fiber epoxy composite increased as the spindle speed deceased. They also deceased as the table feed increased. Second, the good cutting status obtained at the entrance of groove while delamination occurred at the exit of groove, Third, the regular high speed steel endmill was not efficient, thus the new endmill such as coated carbide rooter endmill or dia-mode endmill should be used for the effective endmll operation of carbon filber epoxy composites.