Aiming at the high content of coal slime in raw coal, taking up 20%, the ash content was 45%. In order to study the influence of high-ash fine mud on the heavy medium system, it was found through analysis of various process links that there was a problem of cyclic accumulation of high-ash fine mud in the system, mainly due to the underflow of the hydro-grading cyclone, reaching more than 40%. At the same time, the analysis results showed that high-ash fine mud had a certain degree of influence on the final fine ash, medium consumption and slime pressure filtration. Through the analysis of the status quo of high-ash fine mud in the system, how to reduce the accumulation of mud in the system will be one of the key research topics.