Abstract: In order to decrease the coarse particles in the overflow caused by the short circuit flow during the operation of a hydrocyclone,we designed a kind of hydrocyclone with conical overflow pipe,then the numerical simulation and experimental study were carried out.The simulated results show that the conical overflow pipe plays a guiding role for the short circuit flow,which can be deviated from the overflow port and enters the outer swirl to participate in the separation process directly,therefore the separation efficiency can be improved.The experimental results demonstrate that,compared with the cylindrical overflow pipe,the hydrocyclone with conical overflow pipe possesses higher bottom productive rate.The classification efficiency of －38 μm particles increases from 34.23% to 43.02% by quality and from 35.17% to 44.19% by quantity.With the decrease of the cone angle of the conical overflow pipe,the overflow concentration decreases,the underflow concentration and the productive rate increase,the classification efficiency of the －75 μm particles increases accordingly