The invention discloses a device and method for preparing high-oxygen water. The device comprises a water inlet container, a rotary filler and an oxygen cylinder, wherein the water inlet container is communicated with fillers in the rotary filler via a water inlet pipe; a water pump is arranged on the water inlet pipe; the fillers are fixed on a rotating shaft via a frame; the rotating shaft is connected with a motor; an oxygen inlet is arranged at the upper end of a shell of the rotary filler; a water outlet is arranged at the lower end of the shell; an oxygen outlet is arranged at one side of the shell; and the oxygen inlet is communicated with the oxygen cylinder. The method is characterized in that water enters from the center of the rotary filler and oxygen enters from the outside of the fillers; the content of oxygen in water rises in the mass transfer process; and the rotating speed of the ring-shaped fillers is 100-2800r/min. The process for preparing the high-oxygen water is completely a physical process and the prepared water does not contain any additive and impurity. Oxygen addition is instantaneously completed in the mass transfer process. The method has higher efficiency than the existing oxygen addition methods and has the characteristics of simple oxygen addition flow and low investment.