The effects of structural parameters on the separating capacities of single-cone light dispersion hydrocyclones were theoretically predicted based on the previously developed computational model. The analysis reveals that the capacity of a hydrocyclone decreases with its dimension in the manner of d₅₀∞［KF(］R₀［KF)］while keeping the hydrocyclone number constant. The increase in the semi cone-angle, according to the calculated results, also leads to the increase in d₅₀. However, both variations in R₀ and semi cone-angle does not change the relationship of the reduced migration probability versus the dimensionless particle diameter d/d₅₀. In comparison, the diameters of underflow and overflow orifices affect the separating capacity of hydrocyclones in different manners. They change the cutting size d₅₀, and also the slope in the migration probability curve MP′vs. d/d₅₀. The latter can be used to improve the particle-classifying characteristics of hydrocyclones when low-density solid particles are separated from overflow streams.