Abstract: In order to provide theoretical guidance to the design of a selective crushing separation and crushing device for coal and coal rejects, a discrete element method was applied to study the influence factors of the coal reject impact crushing speed.Taking the material compressive measurement as check basis, an impact cru shing discrete element model of a single particle coal reject was established.A single particle impact crushing test was conducted on the self made impact testing rig an d the correctness of the discrete element model was verified.The discrete element model established was applied to study the coal rejects material parameters and the cylindrical crushing bar radius to the influence law of the coal rejects impact crushing speed.The study results showed that with the compressive strength of the material increased, the coal rejects impact crushing speed would be increased in linear, with the elastic modulus and density increased, the power function form of the coal rejec ts impact crushing speed would be reduced.The smaller radius of the cylindrical crushing bar, the more favorable the selective crushing separation of the coal and coal rejects with certain different compressive strengths would be.