A brewing structure of a capsule coffee machine includes: a body which comprises a water tank and a capsule chamber, wherein a coffee outlet is provided at the capsule chamber; a capsule holder is provided in the capsule chamber; a pump and a heater is provided in the body; the body is hinged with an upper lid; a top piercing mechanism is provided on the upper lid, wherein the top piercing mechanism includes a top piercing tube; a water returner is formed between the capsule holder and the capsule chamber; the capsule holder has a water passage; a bottom piercing mechanism is mounted inside the water passage; a safety valve is mounted inside the body, which is controlled by movements of the top piercing mechanism, for cutting off the brewing water when the upper lid is opened, so as to prevent splashing hot water.