A positioning device for arrangement of a basin false bottom in ocean engineering comprises a laser transmitting system, a rotating platform system, and a control and calculation system. The laser transmitting system comprises a laser transmitter used for providing laser beams. The rotating platform system comprises a two-degree-of-freedom rotating platform used for carrying the laser transmitter and making the laser beams have spatially arbitrary directivity. The control and calculation system is used for calculating, according to given coordinates, the angle by which the two-degree-of-freedom rotating platform needs to rotate, controlling rotation of the two-degree-of-freedom rotating platform, and making the laser beams transmitted by the laser transmitter accurately indicate the given coordinates at the basin false bottom. Compared with an existing manual positioning method for a false bottom, the positioning device is high in accuracy, easy to operate, and rapid, and saves labor and greatly improves the test efficiency.