To realize the real-time monitoring of pipelines, this paper designs a pneumatic soft pipeline outer wall-crawling robot composed of OMCA (outer multi-cavity actuator) based on the motion of the inchworm. The robot consists of a torso and two pneumatic grippers. It is controlled by three air pumps and can realize pipeline linear motion. Use ABAQUS to perform finite element analysis on OMCA and measure its key geometric parameters under different pressure levels, and then test the robot's kinematic performance. The movement speed of the robot on a pipe with a diameter of 10 cm is 0.3 mm/s.