The invention relates to a cement sheath structural integrity mechanics experiment device which is composed of a cement sheath maintenance die and a three-shaft stress maintenance kettle. The cement sheath maintenance die is arranged inside an inner cavity of the three-shaft stress maintenance kettle. The cement sheath maintenance die comprises an adjustable eccentricity upper flange cover, a simulation well wall, a simulation well wall outer protective barrel, a casing pipe and an adjustable eccentricity lower flange plate. The three-shaft stress maintenance kettle comprises a barrel-shaped container, a confining pressure oil cylinder, an oil cylinder piston, an axial load piston, a confining pressure piston, an annular heating element and an electrode. The confining pressure piston is arranged inside the barrel-shaped container, the confining pressure oil cylinder is arranged on the upper end face of the barrel-shaped container in a sitting mode, a silicone oil cavity is formed between the confining pressure oil cylinder and the oil cylinder piston, an axial load sensor is connected with the axial load piston, a pressing machine upper plate is arranged at the upper end of the axial load sensor, the annular heating element is arranged inside the barrels-shaped container, the lower end face of the annular heating element presses the electrode, and the annular heating element is connected with a thermoelectric coupler. The cement sheath structural integrity mechanics experiment device can simulate the actual working condition of the oil-gas well construction, and the measured cement strength of a cement interface conforms to the actual site work better and more accurately.