The finite element method was used to compare and analyze fluid flow and mixing characteristics between three kinds of rotor mixer, 4WS,4WH and 6WI.The UG software was used to build 3D geometry models. The Gambit software was used to be grid division. And model was used to simulate the flow field of three kinds of internal mixer by BirdCarreau constitutive model and Polyflow software. By comparing the average velocity, the axial velocity and the shear rate, the flow patterns of the three flow fields were obtained. At the same time, the distribution of the mixture of the three parameters was described by using the parameters of the particle index, the average logarithmic stretch index, the probability of the particle index, the average mixing efficiency and the residence time distribution. The simulation results showed that, because of the special variable clearance rotor structure of 6WI rotor mixer, the flow field was more easily changed, and its mixing performance was higher than that of the other two kinds of rotor mixer.