The invention provides a water pressure lifesaving device and relates to the field of lifesaving supplies. The water pressure lifesaving device comprises a belt and a water pressure sensor; a cavity is formed in the belt and used for storing a folded airbag and an inflation device connected with the airbag, and a plurality of openings allowing ejecting of the airbag are formed in the periphery ofthe cavity of the belt; and the water pressure sensor is connected with the inflation device. The water pressure lifesaving device is novel in structural design and can play a role in drowning prevention and protection without limiting the free action.