The objective of the study is to demonstrate theoretically one of the ways of improving the quality of continuous mixing of segregating particulate solids. The objective function of optimization is the standard deviation of segregating component distribution over the mixer's cross-section at the mixer outlet, the optimization parameter being the position of segregating component input. It is shown that the input of the component into the position that is optimized over the length of the mixer allows improving the mixing quality. The gain of optimization depends on the rate of segregation and grows with its increase.