How to improve reservoir flowability is the essential question during the development of unconventional resource. The regular enhance oil recover(EOR) methods cannot change the matrix structure and property after hydraulic fracturing. High Pressure Air Injection(HPAI) is a potential EOR technique due to the massive heat generated by oxidation reaction. Beside significant viscosity reduction, the heat can also cause the convention of organic matter and clay thus change the stress distribution and generate fracture in shale which can improve its property. In this paper, shale cores were placed at muffle furnace under different temperature (100-800°C) and heating rate (6-10°C/min) respectively for 8 hours. The X-ray diffraction(XRD) and Total Organic Carbon(TOC) analysis were applied to investigate the change of clay and organic matter in shale. The compressive and tensile strength were measured to investigate the change of mechanical property. The pressure decay test was applied to study the change of matrix permeability. Computed Tomography(CT) scanning analysis were conducted to investigate the propagation of induced fracture. Based on the matrix permeability and fracture number, the equivalent permeability model was established to investigate the improvement of shale cores.