To solve the application demand of silicon carbide diodes in high temperature (>200 ℃) and high voltage (>20 kV) environments, we fabricated a three-chamber shell using a ceramic processing technology of injection molding. Compared with traditional plastic sealing material, the ceramic shell significantly improves the working temperature and insulation voltage resistance characteristics of the device and can be used for high-temperature applications of silicon carbide materials. To solve the problem of shell cracking caused by material deformation after the temperature cycle test, we used ANSYS software to simulate the structural stress caused by temperature change and optimize the shell partition structure. The optimized shell structure passed the environmental stress test. With this structure, shells of different voltages can be developed with single-, double-, and multi-chamber structures. Similarly, shells with different forward rectification capabilities can be developed using different chamber sizes.