Abstract: According to the design of 100MWe HTGR coupled with gas turbine, the energy and exergy analysis were done for each part of the cycle, and inlet and outlet exergies of those parts were calculated. And the exergy loss distribution and exergy loss ratio of each sub-process were quantified and compared with the results of energy analysis done by other papers. The results show that more than a half of the exergy loss takes place inside the reactor core, while the low pressure compressor (LPC), the high pressure compressor (HPC) and the intercooler were denoted by compress system together, play a much smaller role in the contribution of exergy losses than the results in the energy analysis. The exergy loss of the cycle was mainly due to the energy conversion and irreversible heat exchange. The total energy efficiency of the cycle is quite high, and the exergy efficiency is higher.