Abstract: The paper introduces the study and progress on the flow law of oil-gas-water three-phase flow in horizontal pipes at home and abroad in recent years. The focus of the research includes the law of flow pattern, pressure loss, and phase holdup. Many researchers have carried out substantive work and acquired primary achievements. This paper reviews some research activities for flow pattern and pressure loss in horizontal pipes at home and abroad and some suggestions are given for further study on the three-phase oil-gas-water flow in horizontal pipes.