In this paper, a self-developed real-time high-temperature steam heating uniaxial compression experimental system was used to study the compression characteristics and failure characteristics of oil shale under real-time steam heating and after steam heating, separately. The temperature of steam tested in the experiment was set as 100, 200, 300, 400, 500, and 550 ℃, separately. The experimental results show that: 1) The uniaxial compressive strength and elastic modulus of oil shale under real-time steam heating first decrease and then increase with the increase of steam temperature, and they drop to the lowest point at 400 ℃, which is the threshold temperature of mechanical parameter change of oil shale; and the uniaxial compressive strength and elastic modulus after steam heating and cooling are reduced continuously. 2) The peak strain of oil shale under real-time steam heating first increases and then decreases with the increase of steam temperature, and reaches the maximum value at 400 ℃; after steam heating and cooling, it keeps rising. 3) Below 400 ℃, the failure characteristics and instability patterns of oil shale specimens under real-time steam heating are from brittle shear fracture to plastic deformation, sudden instability to progressive failure, and above 400 ℃, they are semi-brittle, shear rupture and quasi-sudden instability; After steam heating and cooling, the failure characteristics and instability type of oil shale specimens are brittle shear fracture and sudden instability below 500 ℃, and are semi-brittle shearing rupture and quasi-sudden instability above 550 ℃.