A soft pipeline robot specifically designed for agricultural irrigation inspection was described. The robot was capable of fast and low-resistance locomotion, achieved through a single-drive mechanism. The robot's peristaltic motion was produced by a linear extension actuator and six pairs of flexible feet, controlled through a single air channel. This integrated approach reduced control complexity and increases mobility. An investigation of the peristaltic mechanism in a single-actuated pipe robot was conducted, along with structural optimization, deformation modeling, and performance testing of the flexible foot and body actuators. A mechanical model was established in order to characterize the driving force and step displacement during the robot's propulsion phase, with its predictions subsequently verified by static experiments conducted inside a pipeline. Gait-based velocity modeling was conducted to examine the robot's motion characteristics. A 3D motion capture system was employed for precise motion tracking, thereby revealing the influence of air pressure and ventilation frequencey on overall locomotion performance. Experiments were performed in a simulated agricultural irrigation pipeline system to evaluate load capacity, adaptability to different pipe diameters, and mobility under varied pipeline conditions. Additionally, a front-mounted visual sensing unit was integrated to enable internal pipeline inspection. The robot achieved a maximum speed of 40 mm/s and carried a payload of 1 kg, enabling rapid exploration within complex agricultural irrigation pipeline systems.