Abstract: The operation reliability of pipeline intelligent robots is the key to the safety of long-distance pipelines. In this paper, the tribological system of pipeline intelligent robots was studied. Firstly, the risks of deposit and pig sticking during paraffin removal were analyzed from the point of sealing leather cup and pressure difference drive of inner robots, and then the unsteady migration model for cup-type intelligent robots was built up. Secondly, the tribological system during the migration of inner intelligent robots was constituted after the pigging rules of complex pipelines, the dynamic characteristics of inner detectors and the bypassing speed control devices were reviewed. Thirdly, the macroscopic and microscopic tribological behavoirs during the mechanical stripping of paraffin from pipelines were analyzed, and three typical tribological models (i.e., unsteady friction, orthogonal cutting and micro particle deposition) were comparatively analyzed. It is recommended to strengthen the research on tribological design and spare parts of pipeline intelligent robots in the future. Finally, the research difficulties and trends on reliability and tribology of intelligent robots were illustrated.