Abstract: Two mathematical models are presented to depict the resistance and the resistance-reduction rate in an air curtain between soil and slide moving on a moist and soft ground. The mechanism of resistance decreasing is studied. Combine with previous theory given by the authors,a calculation is given obtain the area of air film,the sliding resistance and the resistance-reduction rate. It is shown that the calculation is basically in reasonable agreement with the experiment results, thus,the method can be used to predict the above relative parameters. And the important ways to increase the resistance-reduction rate are proposed as well.