Bottle cap facilitating brewing and bottle

The invention provides a bottle cap facilitating brewing. The bottle cap comprises an upper cap body and a lower cap body. The lower cap body is internally provided with an inner cylinder and an outercylinder. A gap is formed between the inner cylinder and the outer cylinder. The outer cylinder is in dismounting-mounting fit with a bottle body. The upper cap body is defined by a top plate and a closed annular side wall. The closed annular side wall is in threaded connection with the upper end of the lower cap body. An extension cylinder is arranged on the lower end face of the top plate in aprotruding mode. The lower end of the extension cylinder extends out of the inner cylinder. A seal cover matched with the lower end of the extension cylinder in a sleeved mode is arranged on the lowerportion of the inner cylinder. The outer circumferential edge of the top face of the sealing cover and the end face of the lower end of the inner cylinder are arranged in an up-down aligned mode. Theinner cylinder is detachabl