Factors influencing the pulp settling property was investigated on the tailings of a mine. The effect of the flocculant kind, pulp concentration and agent dosage on the settling speed was studied in the flocculation settling test. The content of the suspended substance in the upper layer and the liquid-solid compression ratio of the bottom layer were measured. The test results indicate that high molecular flocculants play a role of accelerating the particle settling, and the settling rate is decreased with the increase of pulp concentration and increased with the increase of agent dosage. At a pulp concentration of below 15%, the liquid-solid compression ratio can be over 50%. This experimental conclusion is of direct guidance significance to the tailing thickening by high capacity thickeners in concentrators.