The utility model provides a radioactive isotope operating system and a replaceable module thereof. The replaceable module comprises a base and a medium transmission part, the medium transmission partis installed on the base through a holding part arranged on the base, the medium transmission part forms a flow path through which fluid flows and comprises a pipe, the holding part comprises a clamping groove for clamping the pipe and a containing cavity through which the pipe penetrates, and the containing cavity forms a part for opening and closing a valve of the pipe penetrating through the containing cavity. The radioactive isotope operating system is high in universality, the replaceable module can be replaced after one-time radioactive isotope operation is completed, a pipeline does not need to be cleaned, and radioactive residues cannot be caused.