Abstract: Traditional hydrocyclone,for its inherent structural weaknesses,often causes short-circuit problem and pollutes the products thereby,in order to improve this problem,a new equipment with double overflow is designed,as well as test platform is built. The test results show that the new structure can achieve design objective producing three particle size materials and double overflow. When the content of minus 0. 045 mm materials in feed is up to 62. 25%,only minus 0. 045 mm materials is included in the entire inner overflow,while it reaches 89. 23% in outer overflow,and 25. 24% in underflow.