Abstract: As an ideal source of heat/electricity in deep space exploration missions, RHU/RTG plays a pivotal role in the process of stepping into the space, which largely determines the depth and breadth of deep space exploration missions as well. The principle and basic structure of RHU/RTG were presented, the development status of ²³⁸Pu RHU/RTG was discussed, and the key scientific and technical problems affecting its performance in the RHU/RTG technical system were emphatically analyzed. Based on above the application prospect of RHU/RTG is forecasted, and the development direction of RHU/RTG technology is pointed out.