Abstract: Pipeline robots integrated with smart mobile carrier and pipeline defect nondestructive testing technology are mainly used for detection, coating spraying, joint welding, foreign material removal and other maintenances of industrial pipelines such as oil and gas pipelines. Mode of motion is core technology of the pipeline robots, including active and passive modes. This paper elaborates technical features and difficulties of the pipeline robots using active motion modes such as bionic type, crawler type, screw driven type, vehicle type and supporting wheel type and those using passive motion mode are elaborated and enumerates products and technologies at home and overseas. Based on the above technology, a comparative analysis is carried out for overall performance of various technologies and key technical problems required to resolve for R & D of pipeline robots are proposed.