The invention discloses a bottle cap. The bottle cap comprises a lower bottle cap body and an upper bottle cap body connected to the lower bottle cap body. The upper bottle cap body is provided with a storage chamber used for storing solid powder or concentrated liquid. The lower end of the storage chamber is opened, and the opening position is provided with a sealing film. The lower bottle cap body comprises an upper connecting part and a lower connecting part. An outer thread is arranged on the outer side wall of the upper connecting part. The inner side wall of the upper bottle cap body is provided with an inner thread matched with the outer thread. The lower end of the upper bottle cap body is provided with an anti-fake limiting ring capable of conducting anti-counterfeiting and limiting the upper bottle cap body to downwards move relative to the lower bottle cap body. The lower connecting part is provided with a puncturing piece; and by means of the puncturing piece, after the anti-fake limiting ring is removed from the upper bottle cap body, the upper bottle cap body is rotated and made to downwards move relative to the lower bottle cap body, the inner sealing film is punctured, and the solid powder or the concentrated liquid in the storage chamber and a solution in a bottle body are smoothly mixed. According to the bottle cap, the storage chamber is integrated in the upper bottle cap body, the storage chamber cannot be left in a bottle opening after being taken down from the upper bottle cap body, the volume of the storage chamber is increased, and the situation that the storage chamber blocks the bottle opening, and the liquid pouring speed is influenced is avoided.