An intermeshing co-rotating twin-screw extruder is widely used for producing polymer composites. In order to satisfy properties of the composites, it is important to understand mixing performance of segments. In this study, we discussed mixing performance of special rotor segments commercially named VCMT (various clearance mixing technology) by using a numerical analysis method. The several tip clearances of VCMT work for achievement of both self-cleaning and effective mixing. We adopted a particle tracking method to obtain the following two evaluation indices; 1) residence time for the evaluation of its uniformity and 2) maximum 1st principal stress for the evaluation of dispersive mixing. And we evaluated mixing performance of VCMT by using probability distributions of each index. Moreover, we proposed weighted probability distributions as theoretically better evaluation. The probability distributions of VCMT were compared with those of two kinds of kneading disk segments (KDs). From the comparison, it was found that the probability of VCMT in large 1st principal stress region is higher than those of KDs. As a conclusion, VCMT has better mixing performance than KDs for the geometries and operating conditions that were investigated.