Evaporation duct model is often used to calculate the height of evaporation duct at sea. In order to understand the differences between and methods of different current evaporation duct models, the paper selects four evaporation duct models currently widely used (P-J model, Babin model, NPS model and pseudo-refractivity model) to make a comparison and analysis. This paper first discusses the sensitivity of the models to meteorological elements in the ideal situation, then uses the atmospheric observation experimental data of the offshore layer of South China Sea to compare the results of the evaporation duct height calculated by these four models. The analysis shows that the changes of relative humidity, wind speed and air-sea temperature difference all have large impacts on the calculation of the four kinds of models. In particular, under the unstable stratification condition, the heights of evaporation duct calculated by the four models all decrease with relative humidity and increase with wind speed. The duct height calculated by the Babin model and NPS model are consistent, the calculation result of pseudo-refractivity model and the results of the previous two models are different, and there is an obvious deviation between the result of P-J model and the results of the other three models. Calculation results based on the data of the South China Sea meteorological data indicates that simulation results of different evaporation duct model in the area are slightly different, but the diurnal variation trends of the duct heights calculated by the four models are consistent, the extremely low height values often occur in the morning, and the extremely high values often occur in the evening.