Abstract: The lower separation limit of Ningdong mining area coal washing plant is 6mm. If the -6mm fine coal which accounts for more than 30% in raw coal is separated by dry method, the benefits of enterprises will be significantly improved. Variable-diameter pulsed airflow technology is suitable for fine coal dry beneficiation. This paper introduces the pilot scale system and process flow in detail. The effect of pulsed airflow separation and classification was investigated. According to the characteristics of high content and ash content of -1mm fine coal in Ningdong mining area, the combined process of separation and classification was designed to remove the high ash component step by step. The ash reduction of "separation and classification" and "grading and sorting" were compared and the effect of different air volume combinations of separation and classification were investigated. The result shows that the pulsed airflow achieves obvious ash reduction on 6~1mm fine coal. Constant airflow classification efficiency is higher than pulsating airflow. The combined process of “separation and classification” can improve the separation efficiency through the autogenic medium impact. Separation air volume should be around 260m3/h, and classified air volume range from 78 to 95 m3/h. The ash reduction is higher than 20% and the yield exceeds 50%. The clean coal can be used in coal chemical industry, and mixed fine coal can still be used as steam coal. Thus the product structure is optimized.