Abstract: The separation efficiency of an air-dense medium fluidized bed is directly affected by coal feed characteris- tics. So a systematic study had been carried out to investigate the effect of feed-coal particle size and different wash- ability on its separation characteristics. Moreover,the synergy between projectile strength,air volume and different coal feed characteristics on the separation characteristics was evaluated. The results show that the influence of feed-coal particle size on the separation accuracy is rather prominent. Ep values increase with the decrement of particle sizes. The minimum Ep values for 50-25,25-13 and 13-6 mm difficult-separation coals are 0. 06,0. 07 and 0. 11 g / cm3 , respectively. Washability has a slight effect on Ep . The minimum Ep values for easy-separation coal,moderate-separa- tion coal and more difficult-separation coal of 50-25 mm size ranges are 0. 035,0. 040 and 0. 045 g / cm3 ,respective- ly. Separation accuracy is dramatically improved by the optimization of air volume and projectile strength. The optimum operating process parameters of different coal feed characteristics range over which the separator can operate satisfacto- rily,are found that projectile strength and air volume are 1. 46 and 140 m3 / h,respectively. The mechanism of impro- ving fluidized separation by vibration was revealed by analyzing the relationships between initial bubbles frequency and vibration frequency in the vibrated air-dense medium fluidized bed.