The invention discloses a water-surface demonstrating device. The water-surface demonstrating device comprises an underwater support device, a demonstrating platform, a bionic demonstrating appliance and a side-overturning-preventing device, wherein the underwater support device is provided with a pair of underwater guide rails mounted underwater in parallel; the demonstrating platform moves on the underwater guide rails, and the upper part of the demonstrating platform protrudes out of the water surface; the bionic demonstrating appliance is mounted on the demonstrating platform; the side-overturning-preventing device is connected with the demonstrating platform, and is used for preventing the demonstrating appliance from turning on the side when the demonstrating appliance performs demonstrating movements on the demonstrating platform. The demonstrating device provided by the invention is simple in structure and unique in appearance, at ordinary times, the water-surface demonstrating device is a landscape device, and has no towering sense since having the associated element with water, during demonstration, the water-surface demonstrating device can simulate the posture of animals, the bionic effect is strong, the visual relationship with the audience is changed, during the demonstration, the scene from nonexistence to existence or to disappearing is displayed, and therefore, the charm of the artistic performances is enhanced.