Abstract: Hydrogen is a kind of clean and safe energy, which can help solve many important energy challenges in the future. Nuclear hydrogen production can achieve a large-scale industrial hydrogen production without carbon emission. This paper proposed a hydrogen-electricity cogeneration plan, which coupled with high temperature gas-cooled reactor and based on the thermochemical water-splitting iodine-sulfur process. The hydrogen-electricity cogeneration plan can make full use of the thermal energy derived from reactor. The high-temperature heat is used to hydrogen production from the iodine-sulfur process, and the low-temperature heat is used to generate electricity to achieve the simultaneous output of hydrogen and electricity. A comprehensive exergy analysis model was also established, exergy analysis was performed on the key components of the hydrogen-electricity cogeneration system, and the distribution of exergy loss and the weak parts in the design of the system were obtained. At the same time, the influence of hydrogen-electricity ratio on system performance was explored, and the change of exergy loss of the system was obtained under different hydrogen-electricity ratios. The results in this paper will lay a foundation for further optimization of hydrogen-electricity cogeneration system.