The conventional packaging technique, especially the aluminum bond wire, limits the HT (High Temperature) resistance of SiC-based power devices. This paper adopts the DSC (Double-sided Cooling) packaging structure to remove bond wires, and analyzes the stress-concentration problems on substrates of the conventional DSC packaging structure when applied to HT. The conventional structure is modified by splitting substrates and introducing the HTCC (High-temperature Co-fired Ceramic) interposer to improve reliability, and the maximum principal stress is reduced by half. Based on this, an HT-resistant power module is designed, and the performance evaluation is conducted by simulation. The power-loop parasitic inductance is 4.4 nH, and the thermal resistance is also reduced compared to the conventional structure.