Air film thickness for the air cushion belt conveyor relates to carrying capacity of conveying device,fan pressure and working efficiency. Gas film thickness was required to be kept in a reasonable range,and the target for article was stable and effective operation of the conveyor. With establishing gas film mathematical model,the theory of gap flow and experimental test,the gas film thickness of air cushion belt conveyor was analyzed. The gas film peak type distribution is obtained,which lays the theoretical foundation for the practical application and improvement of the air cushion conveyor.