The invention discloses a bottle opening sealing mechanism of an oil bottle. The bottle opening sealing mechanism is composed of a bottle opening, a one-way valve and a bottle cap; the bottle cap is in threaded connection to the bottle opening; an annular valve seat with an inclined annular sealing face is arranged in the bottle opening; the one-way valve is arranged in the bottle opening and is composed of a valve element, a valve rod, a baffle and a spring arranged on the valve rod, and the valve element, the valve rod, the baffle and the spring are of an integral structure; the lower surface of the valve seat is provided with a valve element sealing face matched with the annular sealing face of the valve seat; the spring is clamped between the valve seat and the baffle and is used for compressing the valve element on the valve seat; and the valve element sealing face is in tight contact with the annular sealing face of the valve seat. According to the bottle opening sealing mechanism, grease in the oil bottle can flow out only through the one-way valve, and air cannot enter the oil bottle from the bottle opening. It is ensured that the edible fat and oil in the bottle is isolated from the air, and the edible fat and oil is prevented from being oxidized, so that the guarantee period is prolonged, and the edible fat and oil is safer to eat.