Screening is a key unit during coal cleaning. One of the most widely used screening technologies for steam coal preparation after removal of fine fractions, is a 6 mm screening method. We propose a novel variable-amplitude equal-thickness elastic screen (VAETES) to solve the problem of material accumulation and screen aperture blockage during the 6 mm screening process of steam moist coal. Kinematics of the screen surface and moist coal during process of the VAETES were investigated by simulation and high-speed dynamic photography. Influence of several operating factors on the screening process was analyzed using Box-Behnken response surface methodology. Simultaneous optimization of multiple parameters was conducted to obtain optimal operating conditions, which were further verified by the screening experiments. The results showed that the average amplitude decreased from the feed end to the discharge end, while the average acceleration amplitudes of the screen surface were > 300 m/s(2). No accumulation of materials and blockage of the screen aperture was observed during the screening process. The importance of factors affecting eta was in the following order: k(f) > A(yc) > D-r. The actual screening efficiency was 87.79%, and the total misplaced materials was 6.77% under the optimal operating conditions. (C) 2019 Published by Elsevier B.V.