A bone drilling cover device comprises an upper fastening member and a lower fastening member. The upper fastening member includes a first base portion and a first coupling portion. The lower fastening member includes a second base portion and a second coupling portion engagable with the first coupling portion. The second base portion is composed of at least one first arm and at least one second arm. The first arm has a length greater than a length of the second arm. A total length of the first arm and the second arm is greater than a diameter of a drilled hole. Through the first arm and the second arm having different lengths, the first arm and the second arm can be inserted in an oblique manner and positioned to the underside of the drilled hole for covering the drilled hole of any bone.
