The invention relates to a varying-stress high-temperature ageing device containing water vapor. The varying-stress high-temperature ageing device comprises a high-temperature furnace fixed on a fixing device (2) and internally provided with a resistive heater (8), wherein a sample clamping device is arranged in the high-temperature furnace, an insulation layer (11) is wrapped outside the high-temperature furnace, the temperature is controlled by using a temperature control device, holes are formed in a top cover and a furnace bottom of the high-temperature furnace, a water vapor input hole and a discharging hole (3) are formed in the furnace body, the input hole is externally connected with a water vapor generating device (13) through a water vapor pipe, and a flow meter (12) and a water vapor valve (14) are arranged on the water vapor pipe; the sample clamping device comprises a clamping device upper connecting rod (5) penetrating out from the top cover (4) and being fixed on a fixing device, a clamping device lower connecting rod (1), a magnet (15) with a fixed weight, an electromagnet core (16), a magnetic control terminal (17) and a base (18), wherein the lower end of the clamping device lower connecting rod is fixedly connected with the magnet, and the electromagnet core controlled by the magnetic control terminal and arranged on the base is arranged below the magnet. The varying-stress high-temperature ageing device is capable of realizing that an ageing stress is adjustable and a water vapor state exists.