The invention, which belongs to the technical field of measurement and testing, provides an experimental device and experimental method for testing the water pressure on a buried water-stopping belt in a deformation joint, thereby solving a problem that the water-stopping belt joint is damaged firstly when the pressure is increased in the existing experimental method of testing the water pressureon the buried water-stopping belt in a deformation joint. The experimental device includes a lining and a water-stopping ring that is formed by encircling of a rectangular water-stopping belt and hasa joint; the water-stopping ring is arranged at the center in the lining, wherein the axial length of the water-stopping ring is smaller than the height of the lining; a deformation joint extending outward from the outer side of the water-stopping ring in a radial direction is arranged at the half part of the lining height; and the joint of the water-stopping ring is arranged at one side away fromthe deformation joint. A pressuring assembly for pressuring one side, away from the joint, of the water-stopping ring is arranged in the water-stopping ring and is opposite to the deformation joint.Therefore, the first damage of the weak point of the water-stopping belt is prevented effectively. The experimental device has advantages of reasonable structural design, good experimental effect andwide application range and the like.