The drill bits adopts bladewith coating, blade can be used indexablely so as to reduce the cost. The cutter body can be used for a long time to reduce the cost. For drill bits with dimensions less than 65, the coated blade is mounted directly on the blade groove of the cutter body. For drill bits larger than or equal to size 65, the coated blade is mounted on the standard cutter holder and the holder is fixed on the cutter body.