A new theoretical approach was proposed for predicting power consumption during rubber mixing. The main assumptions in the theoretical approach include; 1) The mixing of carbon black into rubber matrix is divided into two stages: incorporation, in which agglomerated carbon blacks incorporate into softened rubber and dispersion, in which the incorporated carbon blacks in still agglomerated state further disperse into rubber matrix to become aggregate state, and the mixing rate is the first-order reaction, where the rate is proportional to the remaining carbon black concentration in each step, 2) The mixing torque is originated from viscosity of rubber compound and break-down of carbon black pellets, and it decreases exponentially with mixing time, 3) The viscosity change due to the rise in temperature during mixing follows the Arrhenius law. The power consumption curve was simulated by solving a series of theoritical equations suggested in this work. A fairly good agreement was found between the theoritical and actual power curves. Based on the simulation, the rate parameters for incorporation and dispersion of carbon blacks, viscosity reduction during mixing, time-dependent volume fraction, and power torque, which is very important in rubber mixing process could be obtained.