To overcome the limitation of the conventional hydrocyclone for the ultra-fine particles classification, the novel conical section design of the hydrocyclone is computationally investigated in this work. The electrolytic manganese dioxide (EMD, MnO2) powder, whose size is in the range from 0.21.mu m to 70 mu m, is took as a study case, and the feed solid concentration (SC) is up to 20%wt. The conical section with the modified cone design is proposed to enhance the performance of hydrocyclones. In addition, all the hydrocyclones are equipped with an arc inlet to obtain the pre-classification effect. The micron particles classification with the demarcation at 5 mu m is accomplished in the novel hydrocyclone as the classification sharpness (S-s) is improved from 0.833 to 0.938 at the feed solid concentration of 5% wt. The combination of moderate conical length and modified cone with wide radial space near spigot is the outline of the high classification sharpness hydrocyclone. The dynamics analysis illustrates that the classification performance is attributed to the comprehensive effects of force, residence time, and separation space. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.