Abstract: The excavation shape of the pipeline trench changes constantly with the change of terrain, topography andgeological conditions along long-distance oil/gas pipelines, so it is difficult to accurately calculate the earth and rockexcavation volume of the pipeline trench. In this paper, the geometric model of pipeline trench was established accordingto the technical requirements of oil/gas pipeline trench excavation. Then, the complex geometric model of oil/gas pipelinetrench was divided into two types, i.e., linear volume unit and circular curve volume unit. The accurate volume calculationformula for both volume units are solved by means of the integral method. The calculation formula of circular curvevolume unit is more complicated, and it is checked by fitting the arc with multiple line segments. The result shows that thecalculation formula of circular volume unit is reasonable and can be used to calculate the earth and rock excavation volumeof oil/gas pipeline trench.