For the problems of downburst steady wind field simulation, based on Computational Fluid Dynamic (CFD) methods, firstly, 2-dimensional (2-D) and 3-dimensional (3-D) impinging jet models were used to simulate the downburst wind field, and the characteristics of downburst wind field were studied. On this basis, according to the characteristics that the effect of downburst on bridge structures is mainly affected by the horizontal wind speed, the horizontal wind field of downburst in Boundary Layer Wind Tunnel (BLWT) with inclined plate was studied by using 2-D numerical simulation method. Finally, the horizontal wind filed simulation experimental device of the downburst in the BLWT was designed and manufactured, and the horizontal wind field simulation experiment of the downburst was carried out in the BLWT. The numerical simulation results were compared with the experimental results in this study and the results from the existing literature. The comparison results show that the simulation results of the 2-D impinging jet model for the downburst wind field are in good agreement with that of the 3-D impinging jet model, that is, the 2-D impinging jet model is an effective simplified simulation method for the downburst wind field. The numerical simulation results of the horizontal wind speed and wind field of the downburst simulated by setting up the inclined plate in the BLWT are in good agreement with the wind tunnel test results, and are in good agreement with the numerical simulation results of impinging jet model and the field measured results, that is, the characteristics of steady horizontal wind filed of downburst flow can be simulated by setting an inclined plate in BLWT.