An injection mold for molding a product which has a gap and an inserting groove at a side thereof includes a movable mold and a stationary mold. A fillister is designed in an inner sidewall of the inserting groove. The stationary mold includes an inclined pillar slantwise mounted in the stationary mold. The movable mold includes a movable core and a sliding mechanism which includes a sliding block, a preventing board and a sliding element. The preventing board is further inserted in the sliding block therein. The sliding block is parted from the product to form the gap, for assisting the sliding element to be parted from the product to form the inserting groove and the fillister under the drive of the inclined pillar and the inner end face of the sliding block acting on the other end of the sliding element, when the injection mold is opened.