Abstract: To improve throughput capacity of Ningdong coal preparation plant Meihuajing branch,technological modification on equipment that are undersized is carried out on the basis of upgrade criteria and aim. The result shows that throughput capacity of the plant is increased by 3. 0 Mt/a and reaches 15 Mt/a,the whole process system runs steadily and reliably,power consumption is lowered,breakdown of equipment rarely occurs,and that underground mine production and train loading can be satisfied completely.