The inveniton relates to a small cylindrical acoustic beacon without internal rib grids, belonging to the technical field of marine engineering. The acoustic beacon is characterized in that the innerside cylindrical surface of the beacon body of the acoustic beacon adopts the form of no rib grids; a dry cell is installed in the inner hole formed by a plastic gasket, oak gasket, piezoelectric ceramic ring, oak gasket and supporting sleeve. A battery cover end rubber pad and a battery end part rubber pad are arranged between the inner side of the battery cover and the dry battery, and a batteryend part rubber pad is arranged between the support sleeve and the dry battery to ensure the axial positioning of the dry battery; and a battery cushion made of rubber is installed in the rectangulargroove on the inner side of the support sleeve, and an O-shaped ring is installed in the rectangular groove on the inner side of the plastic washer to ensure the radial positioning of the dry cell. The invention has the effects and advantages of compact structure and simple method, and solves the problems of the integral structure form of the acoustic beacon and the sealing, the pressure resistance and the impact resistance. It is mainly used for a small cylindrical acoustic beacon without internal rib grids.