The invention provides a water lifesaving device, and belongs to the field of lifesaving equipment. The technical problem that an existing water lifesaving device cannot achieve rapid rescue is solved. The water lifesaving device comprises a floating body, the floating body is cylindrical, one end of the floating body is a power end, and the other end of the floating body is an advancing end. A power box which is capable of pushing the floating body to advance in the direction from the power end to the advancing end and is used for weighting is arranged at the power end of the floating body, and the power box is eccentrically arranged relative to the central axis of the floating body. The water lifesaving device has the beneficial effect that rapid responding can be achieved during rescue.