Abstract: As a radioactive isotope of hydrogen, tritium is harmful to human health and environment. Nowadays tritium is mainly from nuclear activity, so it is necessary to study on the source and effect of tritium from nuclear reactors. During the running of high-temperature gas-cooled reactor (HTGR), tritium is one of the main radioactive sources of the primary circuit. Since the core temperature is high, it is necessary to investigate on tritium permeation from the primary circuit to secondary circuit and environment, which causes an unwanted contamination. Physical and chemical characteristics of tritium, the tritium formation sources and release paths of indirect closed brayton cycle with HTGR were expounded. The effect on mechanical performance of equipment material was analyzed and tritium release limits, control method and permeation barrier were presented.