Abstract：Safe disposal of high level radioactive waste is a challenging task facing the scientific and technological world. This paper introduces the latest progress of high level radioactive waste disposal programs in the world，and discusses the key scientific issues as follows：(1) the precise prediction of the evolution of a repository site；(2) the characteristics of deep geological environment；(3) the behaviour of deep rock mass，groundwater and engineering material under coupled conditions(intermediate to high temperatures，geostress，hydraulic，chemical，biological and radiation process，etc)；(4) the geochemical behaviour of transuranic radionuclides with low concentration and its movement with groundwater；and (5) the safety assessment of disposal system. Several large-scale research projects and several hot topics related with high-level waste disposal are also introduced.
