The invention discloses an inner plug for sealing a bottle body which holds liquid oil. The inner plug comprises a plug mouth, a plug cover and a plug cap; the plug cover is provided with a through hole; one end of the plug mouth is fixed on the plug cover, and the other end of the plug mouth extends out from the plug cover; the plug cap is fixed on the plug cover; stripes for sealing are arrangedon the outer peripheral surface of the plug cap; a liquid outlet hole communicating with the plug mouth is formed in the plug mouth; the liquid outlet hole communicates with the through hole; a ladder port is formed in the joint place of the liquid outlet hole and the through hole; and the ladder port is smaller than the liquid outlet hole. After an oil dripping device is used, redundant liquid oil is pressed back into the bottle body under the effect of atmospheric pressure, so that wastes caused by the oil overflowing phenomenon are prevented.