The shear mechanical properties and shear failure characteristics of oil shale under real-time high temperature were investigeted by using a self-developed real-time high-temperature shear system. The experimental temperature ranges from room temperature to 600 ℃ (with 100 ℃ as the temperature interval), and the shear angles are 45°, 55°, and 65° spearattly. The experimental results show that: 1) under the action of real-time high temperature, the shear strength of oil shale decreases with the increase of shear angle, the cohesion and shear stress first decrease and then increase with the increase of temperature, and reach the lowest at 400 ℃; 2) The peak shear strain of oil shale increases with the increase of temperature. The shear strain at 600 ℃ increases by 54% compared with that at room temperature. At high temperature, oil shale shows obvious strain softening characteristics; 3) During the shear test of oil shale under real-time high temperature, with the increase of temperature, the failure stage of oil shale changes from brittleness to ductility, secondary cracks gradually increase, and the failure form gradually changes from penetrating fracture to non-penetrating fracture.