Abstract: The tritium concentration in moderator heavy water of CANDU6 nuclear power plant increases with the operation of the reactor. The leakage of tritium containing heavy water to the reactor building and the environment in gaseous or liquid state will cause radiation dose to the operators and environmental pollution. How to effectively remove tritium from moderator heavy water has been widely concerned in the world. In this paper, heavy water tritium removal technologies are investigated, and the existing tritium removal technologies are systematically compared and analyzed. The advantages, disadvantages and economy of each technology are given.