Abstract: Based on the Euler-Lagrangian method and the liquid film model, the phase interaction phenomena, including the interaction between the liquid drop and continuous gas, liquid drop deposition and entrainment on the wall and the liquid film boiling and evaporation, are modelled for the annular flow in a round tube. The prediction accuracy of the Euler-Lagrangian method for the annular flow is evaluated by comparing the results of the annular flow experiment of KTH. The comparison results show that the mass flow rate of the liquid film obtained with numerical simulation agrees well with the experimental results. The results also verify that the Euler-Lagrangian method, accompanied with the applied flow and heat transfer model, can reasonably simulate the annular flow.