Abstract: There are two kinds of raw coal separation processes in Gaozhuang coal preparation plant,that is pre-desliming or non-desliming. On the basis of coal assay and actual production,some main technical indexes with respect to these two processes are analyzed,such as separation effect of main separation system and coarse coal slime,the amount of clean coal carried into middlings or reject,and medium consumption etc. The results show that the pre-deliming separation process is superior to that of non-desliming.