The effect of the structure of flow field in the hydrocyclone on energy consumption was experimentally studied systematically with orthogonal design. The results show that the effect of the inserted central part on energy consumption is the largest, while that of the underflow pipe is the least. The energy saving performance of the winged core is the best among the inserted central parts. The time-averaged and fluctuating characteristics of pressure structure in the hydrocyclone with low energy loss were also investigated experimentally. Both the time-averaged and fluctuating characteristics of pressure structure in the hydrocyclone with low energy loss are much different from those in the conventional commercial hydrocyclone. The energy saving mechanism was investigated, and the energy saving principles and relevant measures for hydrocyclones were proposed systematically.