Debris flows and mountain torrents are the main geologic disasters affecting the safe operation of long-distance oil and gas pipelines in mountainous areas. It is of great significance to carry out risk assessment on the disasters of debris flows and mountain torrents along long-distance oil and gas pipelines to prevent and alleviate the losses. In this paper, the Guangyuan section of the Lanzhou- Chengdu-Chongqing long-distance oil and gas pipeline was taken as the research object. Based on the coupling-coordination principle, an overall risk evaluation system was divided into two subsystems, i.e., a pipe subsystem and a natural environment subsystem. The pipe subsystem includes 5 indicators: depth, included angle (included angle between pipe and slope unit), wall thickness, defect density and position (distance between pipe and slope unit). The natural environment subsystem includes 9 indicators: slope direction, slope, elevation, normalized differential vegetation index (NDVI), annual average precipitation, height difference, topographic section curvature, distance between pipe and fault, and geological lithology. Then, the weight of each indicator was determined by means of entropy weight method. Finally, the coupling-coordination model for the system was established by using the GIS technology, and the risk level of the long-distance pipeline in this area was defined. And the following research results were obtained. First, the coupling coordination degree is better accordant with the risk degree. Second, the risk degree and coupling coordination degree of the pipeline in the southern part of the study area are higher, which indicates that the natural environment, geological structure and climate change in this area tend to induce natural disasters easily, e.g. mountain torrents and debris flows. Third, the weight of the defect density of pipe subsystem and that of the NDVI index of natural environment subsystem are the highest, so it is recommended to strengthen monitoring pipe damage and vegetation change in the Guangyuan pipeline section. In conclusion, this evaluation method can reflect the actual field situations rapidly and accurately and it is better applicable in pipeline risk evaluation.