This study considers the dynamic model of the rotating flow of a two-phase liquid into a hydrocyclone, and its influence on inherent particles. The geometrical parameters of rotating liquid flow, the relative movement of particles and their separation are described using specific properties of liquid and particles, the energy losses due to viscosity and processing requirements. Theoretical analysis and experimental data lead to a calculation method for the main hydrocyclone design parameters and their optimal correlations. Experimental data and numerical examples for water and milk are presented.