Gas flow field of the bearing usually has a large diameter ratio about four orders of magnitude or above. The simulate operation of gas bearing become very difficult.Through the analysis of traditional model of gas bearing, new type of surface gas bearing was proposed.The numerical simulation model was established and surface type gas bearing with straddletype gas bearing loadbearing characteristics were analyzed. With the help of FLUENT and parametric design function DX module, the numerical simulation precision of this kind of problem solution was put forward. Use above method, numerical stability under the dimensions of discretization model file was obtained. And the simulation research of the surface gas bearing was conducted by using this file. The result shows that the new method of grid independence of numerical simulation is helpful to improve the precision of the numerical simulation, the loadbearing characteristics of surface air support structure is more compact than straddle support structure.