Oil–water flows are widely encountered in petroleum, chemical, nuclear reactors, and other crucial industrial processes. Due to gravity and interaction between phases, horizontal and inclined oil–water two-phase flows are characterized by remarkable multi-scale structure characteristics, such as large-scale stratified interface and small-scale droplets entrainment. Moreover, a slight change in the pipe inclination will lead to significant changes in the local oil–water flow structures, which results in great challenges in the measurement of the interface structures. In this study, we design a 10 × 10 conductance wire-mesh sensor (WMS) to detect the interfacial characteristics of horizontal and inclined oil–water flows. Firstly, we carry out horizontal and inclined oil–water flow experiments. The influence of pipe inclinations on the flow transition boundary is analyzed. The three-dimensional (3D) structures of oil–water flows are visualized based on the WMS measurement response. Then, edge detection is implemented to process the two-dimensional (2D) flow images visualized by the WMS. The influence of complexly distributed droplets is effectively removed by using binary image morphological transformation and watershed algorithm, and thus, oil–water interface structures are accurately extracted. Finally, the influence of the oil–water flow conditions and pipe inclinations on the configuration, height, and length of the stratified interface are investigated.