Abstract: Steam coal is widely used in electric power,metallurgy,building materials,chemical engineering and other fields.Screening is the key link of steam coal processing and utilization.With the development of coal mining mechanization,the content of fine particles gradually increases,when the moisture content of materials is high,it is easy to cause particles agglomeration,screening becomes difficult.Therefore,it is important to carry out efficient dry deep screening of viscous-moist steam coal.The traditional dry screening process mainly is classified by 6 mm,or even more than 13 mm,and the beneficiation proportion of raw coal is low,resulting in resources waste and environmental pollution.Reducing the lower limit of classification is a technical problem to be solved urgently at present. The traditional screen surfaces are rigid screen surface and elastic screen surface,the former is easy to cause aperture blockage,the latter is prone to local fever and aging during screening,greatly reducing the screening efficiency and the processing capacity of screen machine.In order to improve the efficiency of 3 mm dry screening of viscous-moist steam coal,the rigid-flexible coupling elastic screening method was proposed.The kinematics characteristics of rigid-flexible coupling elastic screen surface were studied by means of vibration test,motion behavior of sieve surface and the change rule of flexible region were clarified,and the mechanism of rigid-flexible coupling elastic screening was revealed.The influences of treatment capacity and external water content on 3 mm rigid-flexible coupling elastic screening process of steam coal were investigated by multi-factor successive terms test.The results show that the displacement amplitude and acceleration amplitude in elastic region increased by 87.69% and 98.08% respectively compared with that in rigid region; With the increase of treatment capacity,the comprehensive separation index increases first and then decreases,when the treatment capacity is 2.00 kg/s and the external water content of materials is 6.13%,the comprehensive separation index is above 89.00%.The increase of external water content leads to the decrease of comprehensive separation index,while the external water content rises to 11.01%,the comprehensive separation index is up to 78.92%,it is indicated that the rigid-flexible elastic screen surface can realize the high efficiency of 3 mm dry screening of viscous-moist steam coal.