The bottle plug (1) includes a bottle plug member (2) an elastomer member (3 ). The bottle plug member (2) consists of a gas-tight means and a reuse-proof means and further inserts into the elastomer member (3) being assembled as a unit to form the bottle plug. When the bottle plug is inserted into a bottle neck (4), the gas-tight means provides an expansion portion to seal the bott le neck and the reuse-proof means provides an appearance and the function of indication whether the bottle neck has previously opened or the bottle plug has been used.