Abstract: The transport of U(Ⅵ) and Th(Ⅳ) through saturated single fracture with pulsed injection was studied using a self-made horizontal single fractured granite and an single fractured organic glass as control. Relative concentration change with time and radionuclide transport parameters are obtained. The results show that: (1) The transport ability of these two elements is related to flow rate. The relative concentration is reduced and the tailing phenomena is more obvious while the flow rate is reduced. (2) Under a same flow rate and transport distance, the relative concentration of Th in the fracture is lower than that of U, and the difference between the two elements increases with a lower flow rate and a longer transport distance, which indicates that the transport ability of U is stronger than that of Th as a result of the different chemical properties between these two elements. (3) Comparing with the control, the peak of the breakthrough curve in granite fracture is smaller in value and occurr later with tailing phenomena, which indicates that granite is an ideal material for retarding the transport of U and Th.