Abstract: after the pyrolysis of the low metanomphic coalthe enrichment ofthe mineral would cause the ash content increased and would affect to the late processing and utiliratin ofthe senmi coke.Based on the bas c theoryof the fictaton to remove the minerals taing the semicoke as the study object and based on the analysis on the basic proertythe separation method with the reagent surace modfed ficataion was appied to remove the minerals ofthe seni coke in order to reduce theash content. The resuts showed tht when the modication made with the non- ionic suractant.the ficataton efect as the best.when th mo ficaton made with the anion surfactanth ffct would be the second and when the modification made with th catio suractant th fiect would be the last Mheanwhile the scanmning electromicroscope, wetting heat.infrared spectrum.surace potenial and other analysis methods were applied to stuay surace modification foatatio mechanism of the semi cke.The surfactant and the particle surface adsorption of the semi coke would mainly exist in conjugation eff c of h elecrostatic adsopion hyrogen bonding and aomatic ring.