Abstract: The slack coal production of Chengjiao coal preparation plant had the following problems: the lifting capacity of coal tub was low,its blending effects was poor.Wide installation angle led to surplus slack coal.There were lots of potential safety hazard during system maintenance.Delayed response of blending system brought about noneffective quality control.Redundant and inefficient equipments consumed tremendous extra energy.Stabilize the slack coal production by transforming blending system and products quality automatic control system,homogenizing slack coal quality when it is abnormal.The transformation realize digitization and automation,eliminate safety hazard,reduce the labor intensity.The preparation plant increases economic benefits by 2.169 ×107 yuan,if this technology was used nationwide,it would increase by 2.473×109 yuan.