Pipeline transportation has the advantages of safety, reliability and low energy consumption in transporting natural gas, and is an important transportation route for transporting natural gas. Due to the characteristics of natural gas pipelines with large internal pressure fluctuations, plenty of pipeline bending sections and complex pipeline deformation characteristics, pipeline detection robots are required to have higher detection capabilities, and the study of the motion state of natural gas pipeline detection robots in pipeline detection is of practical significance. This paper adopts the CFD numerical simulation method and establishes the model of DN800 pipeline deformation detection robot. Next, by simulating the natural gas pipeline detection robot under different media and different pipeline types respectively, the motion state of the detection robot is analyzed under different conditions. The simulation results verify the reliability of the detection robot working inside the pipeline, which can fully guarantee the safe transportation of natural gas pipeline.