Abstract: The technology of flotation of ilmenite is optimized with response to surface methodology. The ilmenite concentrate grade is 47.51 % and the recovery is 45.12 % after optimization. Harmonic-mean (harmonic-mean model) was applied to calculate the desirability function, and contrasted to optimizations of flotation of ilmenite by arithmetic -mean and geometric -mean model. The contrast demonstrates that the three types of models are significant, and their predicabilities bear much resemblance. However, the abilities of the three models, in terms of optimizing the process of flotation of ilmenite, are differentiated from one another. In particular, the effect by harmonic-mean > geometric-mean > arithmetic-mean.