It is higher stability to use negative pressure air float system in liquid crystal diode (LCD) glass plate online testing process, in order to compare the influence on the gas film pressure , gas parameters and the impact of mass flow that caused by the size of negative pressure, using the gas lubrication theory, theoretical analysis of the single orifice of the flotation platform is carried out. The pressure distribution law of the film plane was obtained. A throughhole array model was established to arrange the interval between the positive and negative pressure orifice, using Gambit to establish the model and division of grid, the model was given a different negative pressure into the Fluent for numerical calculation, the pressure and velocity distribution profiles of the throughhole array and the center of the array were obtained in all cases. When the negative pressure was -2 kPa, the film stability was better by comparion. Analysis of different negative pressure required to match the positive pressure, to the same bearing, the film thickness of the case of constant, the law of positive pressure changed with the negative pressure was gotten. Finally, from the stability and economic factors, the air supply parameters of the airfoil support platform of the glass optical inspection instrument are obtained.