The deep cone thickener is the key equipment for paste manufacture, and the mud height influences the slurry setting velocity and the thickening density in the thickener. The cylinder's static test shows that the settlement velocity of the slurry is the fastest in the disturbance area and without obvious law; the greater the initial height of the slurry, the larger its setting velocity in the setting area; a uniform settlement velocity is found in the compaction area. The concentration of the tailing with different mud heights is studied by the dynamic mixing facility. The results show that, when the mud height is fixed, the rate of the slurry concentration change is gradually reduced as the compaction time is increased. The rate of the slurry concentration change is the highest within 6h. When the compaction time is up to 12h, the rate of the limit concentration change is very small. The limit mass fraction of different mud heights is 71.23%—74.43% at the same compaction time. The analysis shows that when the limit mass fraction of tailings is above 70%, the limit concentration and the height to diameter ratio have a linear relationship. Therefore, the mud height is an important factor which affects the underflow concentration.