The invention discloses a pipeline crawling robot with a relative position navigation function. The pipeline crawling robot comprises an image collecting part, a robot body, an arm mechanism and a relative positioning system. The image collecting part is used for identifying targets and obstacles in the robot walking process. The robot body is used as a robot bearing structure and is used for being connected with other structures. The arm mechanism drives the robot to move in a pipeline. The pipeline crawling robot achieves work of routing inspection, repairing and the like of the pipeline which belongs to special space, a positioning system with relative position navigation is arranged, only one crank is used in a large-arm driving mechanism of the pipeline crawling robot to drive four large arms to move at the same time, compactness of the mechanism is improved, coordination of the movement of the large arms of the robot is ensured, and the robot can better maintain gravity center stability and balance in a wet and slippery pipe wall. When the pipeline crawling robot faces different pipe diameters in a pipeline, the robot can pass through pipelines with different pipe diameters by changing the bending amount of small arms.