Abstract: The physical model and three-dimensional unsteady CFD models for liquid hydrogen spills in open environment were established.The influences of turbulence models on the simulated results were evaluated.Compared with the Standard k-ε model,the results obtained with the Realizable k-ε model and the RNG k-ε model are in better agreement with the experiment,and the Realizable k-ε model is preferred for the following simulation.Simulations on liquid hydrogen spills with and without dike were then carried out respectively,and the influences of the dike on the spread and dispersion of flammable vapor cloud were analyzed.The simulation results show that the dike changes the spatial distribution of hydrogen concentration and the cloud appearance,promotes the separation of the cloud with the ground,and increases the hydrogen concentration in the near-source region.The dike influences the wind flow filed near the source,which influences the liquid hydrogen spill process further.