The subject of this paper is the estimation of damping coefficients for an air motor rotation experiment. This paper studies three methods for the calculation of damping coefficients under the air motor rotation experiment, including the proposed inverse model, finite difference model and the application of Laplace transform method to deduce an equation for calculation of damping coefficient. In the air motor rotation experiment, the data of experimental angular velocity and experimental torque can be employed to calculate the damping coefficients by using the inverse model proposed by this paper. The advantage of the inverse model is that the damping coefficients, the angular velocity and the angular displacement for air motor rotation experiment can be obtained at the same time. But the finite difference method and the Laplace transform method can not do that. Synthesizing the analytic results, the inverse model proposed by this paper can reasonably calculate the damping coefficients for air motor rotation experiment.