Abstract: Auto brake pad materials belong to the wear-resisting material.The cutter will be wore， need frequent changing knives then to reduce production efficiency and greatly increase the production cost，when it uses ordinary hard alloy cutter to make car brake pads.Diamond coated cutter has good machining ability.In order to optimize the auto brake pad preparation cutter，it uses the CVD diamond coated cutter and hard alloy cutter to do drilling test for brake pad.It analyzed the relations of axial force，torque and rotate speed，load and wear condition of two kinds of cutters.