Abstract: In order to study the classifying and separating effect of composite slime cyclone, the structure of composite slime cyclone was introduced, and the worki ng principle was analyzed, and on the basis of the conclusions of flow field numerical simulation of the classifying and separating effects of composite slime cyclone, th e structures of classification before separation and separation before classification composite slime cyclone were designed, the testing system was constructed, and th e test was proceeded. The results showed two types could achieve obvious classifying and separation effect, but the classifying and separating effects of the classificati on before separation were better than that of the separation before classification.However, the best structure parameters of the composite slime cyclone and operating parameters needed to be studied.