The basic theoretical models established by domestic and foreign researches on hydrogen leakage are reviewed. The characteristics of hydrogen leakage are described from jet structure, diffusion plume, concentration accumulation, etc., and the latest research results on hydrogen leakage based on numerical simulation are introduced. The buoyancy jet models under slow hydrogen leakage are developed. However, model prediction under under-expanded hydrogen jet conditions presents great challenges. The numerical simulation method is very suitable for studying the diffusion law of hydrogen leakage in complex scenarios, but more experimental data are needed. The hydrogen prediction models based on advanced machine learning technology show great application prospect. In the future, hydrogen leakage models need to be further developed to broaden the applicable scenarios and improve the prediction accuracy.