Based on OpenFoam open source software,this paper builds three⁃dimensional flow model under VOF method.Stratified flow,wave flow,bubble flow,plug flow and slug flow with different gas⁃liquid velocities in horizontal pipe are simulated and compared with Mandhane flow pattern.The simulation results of horizontal pipe with diameter of 0.05 m and length of 16 m are consistent with theoretical and experimental results,which verify the validity of the model.The model is used to study the process of plugging,growth and evolution of slug flow.The characteristics of interfacial wave during plugging and the characteristics of liquid slug motion under different gas⁃liquid velocity differences are obtained.The phenomenon of liquid slug head projection and the wave⁃like motion of liquid slug are found.