Based on the synthesis of DDS in fluidization bed，a new method that can remarkably enhance reactivity and selectivity of the copper-silicon contact mass is investigated experimentally. DDS is produced from silicon and methyl chloride at about 300 ℃in the direct synthesis process. The catalyst used in this reaction system is active cuprous chloride powder，which usually forms conglomeration of powder. The conglomerate of catalyst is known to be harmful to the synthesis reaction. Treated by ultrasonic energy，conglomeration of active cuprous chloride catalyst is destroyed，so as to achieve better proportioned dispersion of silicon and catalyst powder. By this means， CuCl catalyst is distributed evenly on the surface of silicon powder， thereby reaction activity and selectivity are increased in the synthesis process of DDS. Using ultrasonic dispersion achieves the same reaction activity with smaller catalyst dosage than the normal dispersion method.