Abstract: The flow of refined oil carrying water along updip pipelines will lead to complex flow patterns. The base for understanding the law of oil carrying water is to accurately identify the distribution characteristics of oil-water two-phase flow in updip pipelines. In this paper, an oil-water two-phase flow distribution characteristic identification method based on image processing was proposed to analyze the images of oil-water two-phase flow in the updip pipeline acquired in the experiment. In this method, the original image is firstly transformed into the gray-scale image to remove the useless information in the image. Secondly, the gray scale of the gray image is adjusted to enhance the contrast and highlight the details of the image. Thirdly, the gray-scale image is processed by means of median filtering to eliminate the random noise in the process of image shooting. Finally, edge detection is carried out on the image to demarcate the oil-water boundary and identify the phase distribution characteristics. It is indicated that this method can demarcate the oil-water boundary clearly so as to identify the phase distribution characteristics of the oil-water two-phase flow in the pipelines. The research results are applicable to identify the phase distribution characteristics of oil-water two-phase flow in various working conditions, and provide the guidance for multiphase flow image processing, especially flow pattern recognition.