CFD model of multiphase flow can be realized by the combination of Euler-Euler model and kinetic theory of multiphase flow,Based on these theories,modeling was used to simulate a liquid-solid flow,distributions of velocity and characteristic of two phase flow was calculated in a vertical pipe.The results show that clusters exist in the pipe and liquid-solid two phase flow was analysised.The main causation of the pressure fluctuation and energy dissipation were caused by the formation,movement and decomposition of the clusters.The results are in a good agreement with experi-mental data and provide theory direction for advanced research of multiphase flow fluidized bed.