Abstract: This paper analyzes the influence of second part installation angle of gravity-fed three-product heavy medium cyclone on heavy discharges,such as iron and so on,and then the numerical simulation of the internal flow in second part which is installed horizontally and obliquely is carried out by using Computational Fluid Dynamics software FLUENT.The test result shows that rational installed angle of dense medium cyclone can facilitate the discharge of heavy material,reduce abrasion of internal wall caused by heavy product,so that longer the service life,and obtained that the optimum installation angle of the second part is -13°.