Abstract: For improving the efficiency of the deep space radioisotope thermophotovoltaic system and the urgent need for domestically produced infrared thermal photovoltaic energy conversion devices, this study conducted research on the manufacturing process of GaSb cells and established fundamental parameters for cell preparation through PC1D simulation calculations. The double diffusion method was employed for cell fabrication while simultaneously a self-made rapid testing system was established to evaluate their performance and continuously optimize related preparation processes. Furthermore, variations in GaSb cell performance under different radiation temperatures were explored. The diffusion law of Zn in GaSb was mastered, and the developed GaSb cells achieved high output power and filling factor under the same radiation spectrum. This work lays a solid research foundation for enhancing efficiency and engineering applications of deep space thermophotovoltaic isotope power systems.