With the exploration and development of oil and gas resources in ocean, desert, polar and other regions, multiphase transport technology has been more widely used. When the mixture flows in pipelines, different flow patterns will be formed as parameters' changes. The dynamics and heat transfer characteristics are varied with the changes of flow pattern. So, it is very important to study the flow pattern for the theoretical research of multiphase flow. In this article, numerical simulation software FLUENT is used and the VOF model is selected to simulate the flow regimes of multiphase flow in pipelines. Unsteady, implicit, segregated solver was used to carry out the numerical calculation, and qualitative analysis was done. Simulation results have good match with the Mandhane Flow Pattern map.