Abstract: In some mountain areas, the pipelines are laid in the pattern of slope crossing to deal with the undulating landforms and complex geological conditions. However, there are some potential safety hazards in this laying mode. Therefore, it is necessary to conduct a quantitative analysis on the slope stability of this laying mode and develop targeted measures to guarantee the safe construction and operation of pipelines. In this paper, characteristics of geological disasters induced by slope crossing pipeline laying were investigated. Then, stability coefficient under three working conditions (original slope, line cleaning slope and trench excavation slope) was quantitatively calculated by using the method of slices based on limit equilibrium theory, and the calculation results were analyzed. It is shown that the original slope is the most stable. And with the progress of line cleaning and trench digging, the slope stability gets worse and worse. And finally, four measures were proposed, including avoidance, governance, protection and restriction. This mode is actually applied to the Shaanxi-Beijing Gas Pipeline for crossing mountain valleys, and it guarantees the safe operation of pipelines in mountain areas under the conditions of geological disasters.