In order to make up shortage of study on air - cushion flow field, the theoretical researches on the airflow in the neighborhood of air - holes and the macro - flow in the cross section for air - cushion were carried out. An example was simulated by use of the standard K - e turbulent model as well as software CFD. The theoretical explanation was well consistent with the simulation results. By comparing the results of numerical simulations on five kinds of air - hole layout, the optimal layout pattern of air- holes was given; it provides a theoretical basis for the design of air cushion belt conveyor.