By analyzing the structural constraints and functional requirements of ventilation pipelines in space stations, such as tapered pipes, C-shaped pipes, and T-shaped pipes, it is concluded that the pipeline robot needs to have the capability of self-adaptation to various pipe shapes and different pipe diameters. Therefore, a three-stage structure consisting of head, waist, and tail is designed, which are connected by a waist posture control module to enable the robot’s posture to change with the pipeline shape for self-adapting to different pipe types. Meanwhile, a passive contraction mechanism composed of springs and sliders and an active extension mechanism composed of linear pushrod motors and crawlers are designed to adjust the leg length for adapting to the changes in pipe diameter. Simulation results verify that the robot can smoothly pass through complex pipelines composed of various pipe types and diameters.