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