Abstract: A bottle cap with additive supply structure, comprising a bottle cap body and a storage cap; the bottle cap body comprises a first top and a first outer skirt part; the storage cap comprises a second top and a second outer skirt part, the second top, the second external skirt and a crackable part form a sealed storage space. In the invention, the additives are placed in the storage cap, the storage cap is mounted in the mounting groove, sealing performance of the storage space is better, and the additives can be prevented from being affected by damp and going bad. The bottle cap body is provided with the crackable part, the crackable part can be opened only by knocking on the storage cap downwards during use, making the additives fall into a bottle body so as to be mixed with bottled contents.