Abstract: For promoting performance and optimizing parameters of planetary twin screw mixers that process a high-viscous flow, an approach for the impact of mixing parameters on mixture homogeneity of the mixing slurry was proposed in this study. Definition of density-based intensity of segregation (DBIOS) was presented to evaluate mixture homogeneity of the slurry. By means of orthogonal factorial experiment design technique and statistical analyses of range and variance, major parameters of the mixing process and their significance affecting the mixture homogeneity were obtained. Experimental and analysis results showed that the delta value of mean DBIOS of ingredient factor of the slurry was 138.275, much larger than that of other factors; Ingredient factor significantly contributed to the mixture homogeneity at a significance level of 0.10; Ingredient of coarse solid phase particle had bad performance of mixture homogeneity. A 3-D sampling model was presented for good representation of the samples being taken in this study as well.