<p>Pipelines in mountainous areas are susceptible to geological disasters such as landslides and water damage, posing significant challenges to the stable operation of pipelines. Accurately evaluating the hazard of geological disasters affecting pipelines in mountainous areas is paramount. In this paper, we select 19 factors, such as geotechnical factors, hydrological and water flow factors, geological triggering factors, factors along the pipeline, and protective measures, as evaluation indicators, thereby constructing an evaluation indicator system. Unknown information was determined by applying the unascertained measurement theory, thereby creating a single-indicator evaluation matrix for each evaluation factor. The analytic hierarchy process is employed to determine the weights of the indicators, and the confidence identification criteria are introduced to ascertain the hazard level of geological disasters affecting pipelines in mountainous areas. As an illustrative case, a specific pipeline section in the Guizhou region of the China-Myanmar natural gas pipeline is analyzed for hazard level assessment and verification. The results demonstrate that the evaluation model established in this article aligns with the actual situation of pipeline hazards. Furthermore, the evaluation is reasonable and accurate, offering a scientific basis and new perspectives for evaluating the hazards of pipeline geological disasters in mountainous areas.</p>