SPEX (R) 8000 Mixer/Mill is a high-energy ball mill which is used mostly for laboratory scale processes. This study deals with an investigation on reactor and ball velocities of SPEX (R) 8000 Mixer/Mill by finite element method for different shaft frequencies. Ball collisions in milling devices are governed by complex dynamics ruled by unpredictable impulsive forces. The analysis of reactor motion and ball in the reactor are carried out by using transient structural and rigid dynamics analysis systems of ANSYSTM software. Velocity/acceleration values of reactor and velocity of ball at 115 rad s(-1) obtained from the analysis are compared with mathematical models in the literature. The results obtained from analyzes are in accordance with the mathematical model has proved the correctness of the analysis model. Kinematic variables for empty reactor and ball are obtained for different shaft frequencies by using the same analysis model. Thus, the purpose of this study is to calculate the working frequency of SPEX (R) 8000 Mixer Mill for different type of materials.